I took mine through Alpine Endeavors. I took the course spread out over five months (from March through August, 2005), as I couldn't afford the entire cost at one shot. I ended up paying more because I essentially had private instruction (except for the review and final), but it was the only way for me to do it. Therefore, any answers on cost for you wouldn't apply.
Marty Molitoris (Alpine Endeavors), I believe, is the only AMGA-certified TRSM Instructor in the Gunks area.
Fortis est veritas