For that money you're going to want a camcorder. You won't look as cool to your friends but it will produce better footage than any DSLR under $500. You could get a T3i if you only wanted a DSLR, but you'd be stuck with the kit lens, and you want something better.
Just some quick research got me this bad boy:
http://www.bhphotovideo.com/c/product/910268-REG/panasonic_hc_v720k_hc_v720_live_streaming_hd.html
1080/60p, and Panasonic is known for great video cameras, between the GH2/3 and the likes of the TM700 and such. It'll be solid, and the image quality will be excellent. The 60fps will do very well for slow motion too.