You have to get an '01 or '02 4runner 340f. Prior years have a downshift cable, ours is electronic downshift: The valvebody is different. When I was looking for mine I determined that the '03, '04 Tacoma 340f would plug and play. Since I could not find one to actually look at I was not willing to risk a shipped Taco trans.
Another source is
Car-Part.com--Used Auto Parts Market they link to the salvage yards. It looks like most are pretty high mileage there or more than the $16k that you have found.
There are a few on Ebay for <$ and you can use a 2wd since your xfer case is just bolted on without any sharing of fluids.
Whatever you end up with, make sure you get the torque converter with it. The 01-02 converter is different internally and even harder to find. Others will bolt up but the ecu will throw DTC codes due to timing on lockup. (which means drop the trans again.-voice of experience here)
Most shops will pick up the tow fee since they can get prices that you can't.. it would be worth checking with the 'new' shop.
Hope AAmco doesn't rake you over the coals for their work. Ensuring that you get all the brackets, shields, nuts, bolts, and bushings over the new place will be interesting.
What a mess. I feel your pain.
good luck,
