With 100k it's barely broken in! These motors are good for 200k+. Here in California $850 would be highway robbery but back in Maine TC's are few and far between so the price sounds reasonable considering it includes the
trans and computer. I would offer him $600 and see what he says. Try to grab the wiring harness too. At least the VAM connector and a foot or so of wire. You'll need that.
BTW, the MAP sensor needs to be changed to a BAP (Barometric Air Pressure). Simply disconnect and plug the vacuum line from the MAP and presto, you've got a BAP!