It depends on whether or not you want your car to be numbers matching. What you're getting is some other transmission rebuilt and you give them yours.
$800 is probably about right. It depends on the area and what labor rates are. Personally, I would want my transmission rebuilt rather than exchange it. Here in Silicon Valley that job would cost about $1,200. But the guy I use knows what he's doing. He installs a shift kit and changes the u-joints. He does a complete rebuild. But everything is more expensive here.
I can't imagine anyone havning that job done for $300. Parts alone would be close to that. In fact I looked up a rebuild I had done in 2000, the parts alone were $500. That price includes a new torque convertor, flex plate, bushings, bearings, modulator, filter, fluid, mounts, and overhaul kit. The labor was a tad over $400. The entire bill came to just under $1,000. On this rebuild, I didn't need u-joints and he didn't install a shift kit. My daughter's rebuild a couple years ago was a little more expensive.
But like I said....this area is very, very expensive. Labor runs around $125 an hour.
