Sorry for not re-responding my PC has been giving me hell the last few days and this is the third time I'm writing this so.. hopefully this one will be sent..
So what I wanted to say is that Cardza is kind of right, kid do find card magic, when presented on stage mind you, rather boring.
The thing is that for kids, cards are a very plain every day object, which turn the magic into less interesting for them then if it was performed with some big magical apparatus they never seen before (when usually the opposite goes for adults). Kids, and this goes for 5 year olds as for 10 and 11 year olds, prefer magic that is simple yet impressive, what it means is that they prefer something that is simple, or is rather easy in it's technical side if the trick itself look amazing, more then a trick that looks impossible but on it's outer look is quite plain (for example, kids will prefer you producing 20 spring flowers out of a hat, then you making a signed card appear in your wallet), now that doesn't mean you need to go and buy all the expansive colorful apparatus and production items you find in a magic shop, it means you need to learn how to harness your skill in card magic and turn it into routines that will indeed involve cards, but still be interesting for the kids.
So how DO you turn a card trick into a routine that will interest the kids?
Here are some tips and routines that will help you customize routines for yourself with little to no money:
*First there are two basic ground rules about magic for children:
1)For the trick to have impact on the kids it needs to be either funny, or amazing or both (again, the term "amazing" changes by the age, but for the harder to contain kids, that are usually the 5-11 year olds, amazing is more about how grand is the climax rather then what the climax means, making a sighed card appear in your wallet, as said, may be so impossibly amazing, but for kids it's rather plain, revealing a chosen card by a jumbo card, or a big silk with the card name on it however, is maybe a lot easier and less impossible, but more amazing for most kids)
2) Keep it short and sweet, what it means is, don't do a routine that has a build up that is too long (unless it has humor in it that will keep the kids attention)
*Now that doesn't mean you need to make a carnival out of every card trick, you can build 2-3 more amazing routines, and between them insert 1-2 less impressive short tricks (but again keep them swift, and deferent from the other ones), you can make the more "mild" tricks more interesting by presenting them together with flourishes or small card manipulation bits that can also be comical (like producing a fan of cards from behind a kids back), if you are good at card manipulation you can even do a full manipulation routine instead of a magic trick.
*you can save the more close-up/simple card tricks for your walk around, things like ambitious card, 4 ace routines, even simple color changes can be very interesting to kids when done face to face under their nose (and slowly so they can understand and grasp what is happening).
*On stage, for kids even a simple "choose any card.... is this your card?" trick can turn into an amazing act, again by comedy, and by a big finale/revelation. Here are a few ideas you can use:
*have the chosen card name, or a jumbo copy of it on your back, let the kid "choose" the card, then try to tell him what his card is and fail, act confused say you are going to read the tricks instructions, turning your back to the audience on the way. And you can do it as a running gag, come back, again fail and again turn your back, and you can do it 2-3 times. You will know it's working if the kids will be yelling "on your back".
*you can have some double sided scotch tape on the forced card, and after the kid chooses it, steal it, and stick it on his back (do it as you "come to show him something" that way you can have a reason to get close to him and stick it), then you can produce cards from your pocket, shoe ,the deck, etc. saying "your card is here" and fail, then ask the kid to turn his back and wisper in your ear what the card is, all the kids will be laughing, seeing the card is on his back, and then you can tell the kid he stole it (not in an angry way, or this can be miss read), take the card off, and that's it.
*Another thing, and that's something I sometimes do on my own kids show, Is this: buy a cardboard sheet, and on one side write "If the card is X clap your hands" (when instead of X you write the card you are going to force), and near the writing paint a copy of the card (or just glue a jumbo copy), and on the other side of the cardboard write "Keep looking at the card". then on performance, force that card, and tell the kid to hold the card with it's face to the crowd and look at it's back (without you seeing what the card is), then tell the kid you are going to try and find out what the card is, go behind him and lift the sign, the kids will of course clap their hands, and eventually the kid holding the card will turn to you (to see why the kids are clapping for) and when he turn his head, swiftly turn the sign so it will now shows "keep looking at the card", you can do it again, but don't do it more then 2 times, eventually put the sign down and tell the kid you can't find what card it is, tell him to place it back in the deck, control it to the top, and then basically you can do what you want, make it "jump" from the pack (telling the kids to yell "jump" to make it jump), have the kid choose a card, top force it, so it will look like the kid re-choose the same card, you can palm it and produce it from anywhere, etc.
*another way for an amazing revelations that won't cost you too much money but the kids will flip is this: get an old white bed sheet you don't need (or just buy a cheep large piece of white fabric on a fabric store, shouldn't cost you more then a few bucks), and get some paint (any paint will do really), and paint on the sheet a card (make a simple one like the ace of diamond). then roll it on a broomstick or something like that, and find a place to hang it on the stage behind you, then all you need to do is to attack the sheet's edge to a string, force that card, and while trying to find what is the card pull the string, or have someone do it for you so while you try to find out what the card is, a giant copy of it opens behind your back.
*Another nice thing is the magician's insurance trick, print a card on a paper, and fold it (with the printed side inside) into quarters and on one of the sides write "the magician's insurance". then on performance patter about you having insurance if a trick you do doesn't work, then force that card, shuffle the cards, you can steal the card and have the deck checked for the card to show it's gone, but I find it makes the routine too long, especially if you let a kid look for it , then you say the card traveled into your pocket, and pull a wrong card from there, and then keep pulling cards from any where, your shoe, your sock, you pants, what ever as long as it's funny, and then pretend to give up and say "well at least I have my insurance", take it, and open it to show the selected card printed inside.
Also about what you said about balloon sculpting, the basic stuff like hats, dogs , swords and flowers are very very easy to do, personally I learned how to make them in 15 minutes or so, and now I offer to parents me staying for half an hour after the show to make balloon for the kids for an extra 20$ (and I haven't got a single show where the parents said no for this offer^^). but any way, a lot of balloon packages already come with instructions for the simple stuff, and they are rather good, but it's not the same as seeing it made in action, so what I would suggest you to do is get someone that knows the basics to teach you, and from there you can learn on your own, or if you are willing to pay, buy one of the instructional DVD's, they are probably the best thing beside someone actually teaching you, and they also have more complex things in them, personally I purchased the DVD "Balloon Magic Made Easy" and it has been very helpful for getting me started.
Also you can find some instructions for simple and more complex things on this link:
http://www.mbd2.com/kidsstuff.htm
Oh and a small tip: buy a balloon pump, it worth the money believe me!
Have fun, and good luck.