No tranny shop is going to give you an exact estimate until they pull the tranny and look at it. That usually costs $300 to $500 depending on the model and make vehicle. After they pull it and look at it you should get a firm estimate of total rebuild cost. The pull and relace cost (autopsy) is what you pay if you don't get it fixed, and its always part of the total cost of rebuild if you have the work done. $650 does not sound way out of line for the rci, since the exhaust system has to come off to get to the tranny and it includes the time breaking down and looking at the tranny and coming up with a repair estimate. Sounds like the $2450 covers the replacing of all soft parts. I'm assuming they have diagnostically eliminated solennoid and other external electrical problems or mounting issues. Make sure you ask if the price covers any hard parts, like gears or pump, and if price includes fluid and torque converter. $2450 for total rebuild with all soft parts does not sound out of line if he has a good rebuilder. Warranty is probably cost specific, so if you get a lifetime warranty with the job you are probably not getting screwed. Get BMW customers references and call them. Generally I would think the RCI for that tranny would be about $350-450 and complete soft part overall with converter (rebuilt) would be in the $2000 dollar range, making it about a $2450 job, depending on warranty (should be lifetime) or about $2000 for 1 year warranty. Call around and see what others would charge, although they are going to resist quoting over the phone.