Only having 31s is really kinda small w/ a 4" lift. 31s fit w/o rubbing on the stock suspension.
I only bring this up b/c it suggests it once had larger tires... you don't spend that kind of coin on a Yota lift for no reason. Given this, it means one of two things:
(a) some PO regeared the axles to match for bigger tires, so now the power curve could be way off using the 31s, or
(b) they ran bigger tires and did NOT regear, in which case there could have been alot of stress on the diffs, and you could be looking at issues or replacements soon.
Eitehr way, you need ot be sure to find out as much recent history as possible so you know what you're getting into.
$2500 isn't a bad deal, but it's not smokin' enough to just jump on it either... e.g. not unwarranted to hold back and dig up more inof...
just my first thoughts.