Hey Gadget, I'd like to chime in with my (learning) experience with my 99 4x4 SR5 Xtracab:
Bought it from a (short-term) 2nd owner who knew the orig owner for all the vehicle's life. All original, 104K on the clock, and long story short: original owner was an old dude who bought it new and just DROVE it, (I found out along the way after I bought it) performing almost no maintenance whatsoever. Yes, low miles, but this dude used it for his "fishing truck" and just drove it into the ground. I SHOULD HAVE done more research and looked at it a LOT harder when I drove the four hours to go see it ($7700 was way less than everyone else in my area was asking...for a reason, it turned out), but it ran well, had low miles, no rust, and was in my price range.
The big gigantic issue I ran into first was that the engine was horribly sludged and burned oil like it ran on it. I took it in to get the "power flush" and they took photos when they removed the valve covers--I was horrified and embarrassed. Afterward, it ran about 50% better. When I replaced the timing belt, tensioner pulley, water pump/thermostat, and all belts and hoses, it ran 100% better! After those two big things were taken care of everything else has been little fixits here and there but nothing major. I replaced the ORIGINAL suspension recently with OME suspension all around and that has been another gigantic improvement!
I guess what I'm saying is: be prepared to spend--how much depends on your detective work prior to the purchase. This truck has done a yeoman's duty for me, and I love it, especially considering what I was asking it to do right off the bat (3hr round-trip commute almost every day for the better part of a year!), but I could have been a bit more patient in my search and might have even saved myself some (read that: a LOT of) ass-pain. In the end, though, I've learned a LOT along the way (thanks, TacomaWorld!) and know without a doubt that the parts used were top notch and the work was done right (if not the first then the second or third time!) because I did it myself.
Very satisfying. And that 3.4L engine is damn near bulletproof.
Hope this helps, please keep us posted!