I was looking at one point as well but gave up due to sudden lack of funds due to some family issues last year, but by next spring I'll pick one up at the local pick a part. My intention was to disassemble one to get some general knowledge of them and how they work, and do a rebuild on it only issue is its kind of a PITA to swap transmissions just to see if they work or not LOL...so not really sure it would make any sense to do that just to have it lying around.
If I recall my local pick a part yards want $150 or $250 for a transmission can't remember for sure, and like $250-300 for an engine....Saw a guy a while back pulling a 12 valve cummins engine out of a freshly wrecked Dodge Ram 2500. On my way out the door I asked the clerk what they charged for a diesel he just pointed to the board and I swear it was like $250 or 300 for an engine, I said same cost regardless of gas or diesel he said yep...well whoever got that engine got a killer deal, as it was of course a running/driving truck before the accident. Seen people pull engines and transmissions in cases like that...I asked the guy that was pulling the engine what his plans were and he said he was pulling it to resell it for about $5-6k....damn must be nice to have that kind of time and money to go spend pulling engines from the pick a part...course I guess that would be maybe 1/4 or 1/2 of someone's annual income if they could do that once or twice a year HAHA!!! The guy pulling that engine though was a mechanic so probably had the opportunity and possibly had a seller or vehicle already for it but dang $300 for a $5-6k engine is a steal.