I have an opportunity to pick up a 2003 Xterra for $500. Owner is a friend and says it needs a new transmission. I've been looking online and it seems I should be able to get a new/used transmission from $600-$1000. KBB on the thing is ~$4k if I fixed it. Anyone ever tackle one of these or something similar? Is it something I could do in the driveway? Or should I leave it up to a shop? Obviously if a shop quotes me too high, I'm not even going to buy the thing. I'm just trying to make a buck/ have a fun 4x4 for the remaining winter months.