Im sure we have all heard it before but the best and in someways the only way to progress is to practice, practice and some more and then after that practice it all again.
Its a hard thing to do but you really should save your hard earned cash and really concentrate on the items you already have in your possession and you will, in time begin to master thoses and have great fine tuned skills. Otherwise you will end up with 'drawers' full of effects which you can't do correctly or good enough instead of a few great effects you have well practiced.
I know you state that you don't have a lot of cash to buy stuff with, but if you're just starting out, the plan is to READ and READ and READ!!! Try 'Complete Course in Magic' by Paul Willson. It retails at just £17:49 and is about 2 inches thick and filled with tricks and tips from the basics to the more interesting stuff. I have just bought this for my son for his birthday and he can't put it down. Go to www.alakazam.co.uk for more details.