I just completed by first R&R in my c6...rebuilder did it for $625, I did the pull and install, manual tools and a Harbor Freight tranny jack for $90. $50 fluid, and I sprung for a fresh rebuilt starter while I had it out anyway, another $40. Quotes I got for complete 'in and out' was typically $2200, with one guy at $2K even, which was the lowest. I had only spent $3K on the truck 20 years ago, so I decided I was most comfortable doing it myself and done right.
edit: forgot some details, bought new 3/8 flange nuts and threadlock (torque converter, I destroyed 2 of the 4 nuts with a chisel) about $8, and I had to cut one of the cooler lines (front) so needed a 5/16 patch brake line with a coupler, another $11.