Same here... $125 from Red Regal T... It includes the Vacuum Block to attach to the brake booster, but I opted to get an aluminum TTA vacuum block instead.
Installed it myself about a year ago, saved a little money there. A new PM would have failed on me by now, or at least started to act up (my past exp. with 2 NEW GM UNITS and one remanufactured which lasted a whole week)
Purchased a brake booster filter, new vacuum line, hoseclamps, pedal foot pad, and new check-valve, (Didn't need it... CV was OK).
Total cost in parts about $185 + Shipping (About $150 if I just used the supplied plastic vac block)
If you decide to do it yourself, I recommend picking up a cheap pneumatic 3/8" ratchet (Or rent/borrow one.) if you have a compressor. Makes taking the pedal arm nut off and tightening it up much easier at the top, under the dash. It takes a steady hand to get that b1tch started though!
MasterPower Brakes also sells a conversion kit for GN's. Looks like a first rate unit... I almost got that one.
(Glad I didn't. John (Red Regal T) came through for me.)