i was driving around today doing some burnouts and stuff and then i went to drive to my buddies and when it went to shift into 3rd it just started reving instead of shifting....i think my tranny went out

and if it has gone out any websites with good reliable tranny for cheap (under $700)

 

Sounds like you've hurt the 3-4 clutch pack, which is the most comon failure in a stock 700r4. - You may be lucky enough to find that you heated the fluid enough that it will hold again after cool down, though it may not last long. If it holds after cooling down, change the filter and fluid, keep your finger's crossed and save up some more money. $700 won't buy a good 700r4, not even what I'd consider a decent stock rebuild.