I just purchased one from a member here w/29K from a bike he triked and I paid $225 + shipping which came out to be $243. At that time Pinwall was sellling some that had 40-80K miles ranging from $150-$200 + shipping.
Pinwall, what I understand, is a used bike parts dealer and it's no telling where these things came from and how were they taken care of. Hopefully a VRCC member would be more honest, hopefully. Of course Pinwall does have a guarantee of sorts and people that have dealt with them have good things to say about their transactions.
Just keep looking because, the way my luck runs, since I bought mine these things will start popping up all over the place for $50 that have like 500 miles on them!!!
I lucked into this low mileage 1999 triked-Interstate stuff for $330 recently (there's a good drive shaft in there):


The fine final drive I've had on my bike for 30K came from Pinwall, it looks pretty much like the above (on the inside, not the outside)...
My buddy Henry has a Pinwall final drive on the way, I bought it on the phone and told them I wanted an awesome one, like the
other one they sent me... we'll know in a few days... There's nothing at Pinwall now (well, I looked yesterday) except a gouged up one
with the shock bolt broke off in it. It might be functional, though... I wouldn't think much of receiving one that was as worn out as
the one I wanted to replace, and I've never heard of anyone receiving a worn out one from Pinwall (fingers crossed)...
-Mike