You want more?
1.) Cut a large square hole in the mobo tray to access the socket back plate. This makes it easy to switch cpu coolers without having to remove the whole board.
2.) Apply some sound dampaning material to the base of the case. It won't make a large different in noise, but acts as a good dust catcher and I think it just looks cleaner. I know your on a budget so I might have some left over from my last build.
3.) Change the front panel leds to yellow ones and like I said before, you can mod the case fans/ cathodes with yellow as well. Now modding all your fans to yellow leds will be very time consuming, so I was thinging maybe white leds will light up the yellow paint. We might be able to find yellow fans
check A.C.Ryan's website, they have lots of uv colored fans.
4.) With the paint jod I wouldn't do the inside 100% yellow. You want to even the theme out nicely, for example: paint the mobo tray, inside/outside rear, and top of the case Yellow. With the botton black and drive bays black. I can draw out a good example if you want.
5.) Have you thought about mounting a fan on the bottom as intake? This will be very effective if the case will be off the carpet and on a table or stand. If you want to do this I would get taller feet so air can actually get under there. If you really want to be flashy you can get led case pegs.
Do you have a Lowe's or Home depot near by? They have Plexi-glass that you can cut to the size you want.
To help with more mod idea's, do you have the specs for this mod yet? What psu, cpu cooler, mobo etc are you using?