I agree with David's comments and that is why I bought a new one instead of used. Mine is an SR5 I just got this past week. Knowing that they will discount those about $2,700 +/- for cloth brought mine down to $32,500. I didn't get a lot of bells and whistles though. But it came standard with many items I wouldn't have thought to add. The only options on mine were: running boards, cross bars on the roof rack and floor mats. I'm pretty simple and didn't want/need all the goodies that come with the more upscale versions. Where am I going here...
If you can see what the one you're looking at originally listed for and then estimate the standard discount they would give on it; and compare that to a new one just like it and a discount they would give on it (it might be in the $5K range since there's more to work with), that might help determine if it's a good deal.
4Runners definitely hold their value and I did find the used prices were very close to the new prices after dealer discounts. My thought is, take some time and decide what you want in a 4Runner. What must you have? What can you live without? Then compare the different price points. Maybe this one has everything you've ever wanted and it might be a good price for it too?
Good luck.