I have three of them in different vehicles. I bought all mine used on Ebay. They ranged from $750-$1300. All work fine. If you are not opposed to used units, they come up every so often on Ebay or if you like scrounging in salvage yards look in 80s era RVs. A lot of them were used there. As mentioned, the "P" type units are a lot better and can be easily recognized by the large GM turbo 400 type speedometer gear in the tailshaft housing.
That's interesting, with price tag for a new one, I never really considered them viable, I never realized you could pick them up used in the 1k range.
For me, I have little to no interest in doing the drag week thing (I have a small child, spending a week going off and playing with cars is just not in the cards) and I am retired, so I don't have to commute, even in my truck, I rarely use the od, and it has 4.56s, for the majority of the driving I do, steep gearing is fine, but it you can get a GV for around a grand, that does make it more interesting.