There aren't many good options to make an impact for less than $500. The only ADJ light package of which I am aware for that little uses incandescent lights (which you won't want to use in the long run). Hopefully your DJ company will do well enough that you can step up to ADJ or Elation lights soon.
In the meantime, something that does a pretty good job and will be useful over the long run is the KAM Parbar. For a cheap LED light set it puts on a pretty good show using its foot controller. Check this out:
http://www.youtube.com/watch?v=HIi4KwGLVw4Later you can include it in a DMX set up and control each light separately. Even better it is REALLY portable and easy to set up.
You will have to order it from an English distributor. Don't worry about the spec that says it needs 220 volts, 50hz. I use one of these and just plug it straight into US outlets and they work great.