Seems like a solid price for the rig! Like others have already said- check underneath well for rust. You should be able to find plenty of info on spots to check-and how to check them- by searching. Just Google "3rd gen 4Runner rust" or the like. Back around the lower rear link mounts of the rear suspension might be the most worrisome area to find significant rust.
As far as "how much per year" goes- it really depends on your local mechanic rate. Since I do everything myself, the cost is significantly reduced for any given project. That said, I would plan on approx $600/yr for a shop. Some years you won't spend anything, and you might have to spend $1,800 or more one year. That would pretty much only be if your trans went tits up. Supposedly, the '01/02 trans are known to have an issue. When I bought my '01, it had a weird issue, and I believe it had to do with some solenoid- some say the torque converter is what "goes out".
At any rate, plan on replacing spark plugs/wires/coils, all oils/fluids, radiator, timing belt and water pump, valve cover gaskets, and lower ball joints as soon as you are able to. He mentioned a certain coil and a certain spark plug were replaced, and that's just funky. When one needs replacing, it's best to just replace them all. Always use OEM parts, as they really are higher quality, and the cost is rarely higher than what they're worth. But it does help to buy the parts online.
After you do all the above, you really shouldn't have to worry about anything for a lot of years. Some suspension bushings here or there, tie rod ends, and regular oil changes should be all you can expect for another 100k miles. I would replace the spark plugs again at 50k.
