Hey guys, i just went into a ditch and hit a couple trees, left some big dents, and now my passenger side drum brake locks up when i barely even touch the brake! What could be causing this and is it an expensive repair?

Does it lock and stay locked untill you release the brakes, or does the abs kick in??
Also did you take off the drum and inspect for anything unusual??
If your wheel is locking up and the abs does kick in(allowing the wheel to release/lock rapidly)..I'd be suspecting a leaky slave cylinder for that wheel.
It's the most likely cause and would not set you back a lot in cash for repair..the part is about $30-40 cnd and would take i figure an hour "max" to replace and bleed.
If you wanna see if this is a problem your car has, pull off the the drum for the wheel that locks and note if the slave is leaking..if it is, that's your wheel locking problem

An easy 'check' is to jack up that rear wheel and

see if it wobbles because the axle is bent....

(Axles and front spindles can be straightened at

a good machine shop.)