What should I wear to the casual dance?

I don't have anything to wear. Last year I wore a mini skirt and I felt like a tramp (it wasn't really short-short) it was hard to have fun without worrying about it flipping up. Everyone else wore jeans but this year it's going to be a little too warm for jeans and plus that's plain. What should I wear? I hate to ask my mom to get me an outfit but the only clothes I have right now are jean shorts, plaid bermudas (which I wore for picture day I'm not going to be an outfit repeater) and a too-tight cargo skort and cheerleading and running shorts. WHat type of thing should I get if my mom lets me go shopping? Where should I go to find something inexpensive and cute?