I can offer some assistance if you're interested. I was married in Las Vegas last year, and I wanted to incorporate some gambling/magic aspects into the favors we created for our guests.
We looked into having custom cards printed up, and there are a ton of options out there. The great thing about these companies is that they will send you examples of their work, so you can get a hands-on feel for the quality. Bear in mind, you won't be finding Bicycle quality (unless you want to pay a pretty penny), but for what they are (gifts), they're fine.
We were originally going to have custom printed playing cards done, but given that I wanted Bicycle quality, I opted to use actual Bikes and made a few extras, instead.
Among the favors were:
Custom printed poker chips
Custom printed Playing Card tuck cases
Custom "joker" cards - with a special surprise
I was able to print the cards myself. I don't know if you have a high-quality printer, but if you do - it can be done, and the quality is very good. I made a set of two "jokers" for each pack that we gave away. This consisted of an illustration I made of the bridge in the Venetian Hotel (the location of our actual wedding). One was a regular illustration, the other was a fun little "bonus" I put in where the gondolieri is holding a playing card - allowing me to do a few "prediction" tricks during the reception. This was just a fun gag I threw in for fun. The only cost was a few packs of blank faced cards - which you can find for a deal in most places.
The tuck cases weren't a typical thing. Since I work as a designer for a living, I was able to do a trade of services for my tuck cases. This was incredibly fortunate (any designers out there will know), since the die-cutting alone would have cost me an arm and a leg. Some of the custom card companies out there offer custom-printed tuck cases, while others deliver the decks in a case with a clear "window" letting the back design show through. These options are just as good, I just got lucky with this one.
Another idea you can do (which was my original idea) was to buy some blank sticker paper and print your own tuck case fronts, and just stick them to a regular deck of bikes. My test copies were done this way, and they were fine.
The poker chips were the result of many months of searching and pricing. Unfortunately, if you're not in the US, I can't really help you with this one - but if you have questions, I'd be glad to help. We were able to get 1000 2-sided, full color 11.5 gram composite chips for a decent price (roughly $200). The quality was absolutely phenomenal. Once again, these companies will send you samples of their quality. With this kind of thing BE SURE TO GET SAMPLES! Some companies have different processes, and the quality is vastly different depending on which one they use. I will ask my wife about the company we went with. She knows more details on these process differences, so if you're interested in that kind of thing, let me know.
If you're looking for custom playing cards (individual cards and not entire decks), there's two excellent resources that I know of.
This site:
http://www.magicbycardmaker.de/pageID_5109150.html
Is run by an incredibly helpful man named Bernd Maucksch. I contacted him to have him print up my "joker" cards. Unfortunately - my particular design was too detailed for him to successfully replicate, but this is in no way a reason to not look into his services. His quality is top-notch - and he is extremely quick with replies and contacts. I couldn't use him on this particular job, but I will certainly consider him in the future. I do believe he has the capacity to print full decks, as well.
If you're looking for custom printed decks (not Bike quality, but good) a great company is Kardwell.
http://www.kardwell.com/
They offer a number of services, and their prices are reasonable. Please note, this is not a cheap thing - so if money is a factor (which it was for us), then it may not be the best option. It should also be noted that these kinds of companies can print different shaped cards as well (some of the samples were circles and even heart-shaped). Something to think about.
That's some info for you. I have more if you're interested. Just wanted to get some basics down for you. If you have any other questions/comments - feel free to ask.