A quick peruse of auto trader shows that most if not all of the v8 4runners are going for $15k at least. I suppose if you start searching craigslist ads you might be able to find one for less, but it will likely have more miles on it.
As for the 4th gen 4runner, the platform itself (frame, chassis, interior) is pretty solid and holds up well. The stock vehicle sits kind of low for a body-on-frame SUV (which I'm sure Toyota did to squeeze out every MPG they could for EPA ratings), but if you start adding in aftermarket suspensions, that shouldnt be an issue. I never heard about any major recalls or technical service bulletins for the 4th gen 4runner, but that doesn't mean there weren't any. It would be to your advantage to check the NHTSA for all relevant recalls and technical service bulletins.
I don't have any experience with the V8. I've heard pretty good things about the engine in terms or reliability. I think I recall the timing belt, or something like that, being a common maintenance/wear item, but other than that a lot of owner feedback I've seen has praised the engine. Fuel economy will suck compared to the V6, but that is to be expected.
As someone else pointed out, T4r.org is a good place to discuss all things 4runner. I think the 4th gen section of the forum is still very active, so you should be able to get very detailed feedback there if this forum doesn't provide the answers you are looking for.