Where can I get cheap doorknobs with locks?keys included.?

My current doorknob locks from the inside, but instead of a keyhole on the other side it has a small hole. I don't want to mess around with metal rods trying to figure out how to unlock and lock it from outside, or going through my widow to unlock it. I just need something cheap, but works good(when i say cheap I mean 10-12 dollars is the maximum i can pay)