I think it depends on your locale. The OP is in Colorado and I'm sure there are a bunch of offroad clubs, Jeep clubs etc and D60/14b ff is a popular upgrade right now. Around here a SRW Dana 60 could go for $1,000 in better-than-good shape and if it's got a Detroit locker that puts it up closer to $1,500. The 14b ff is worth $150-$250, more if it's already set up for disk brakes. A Detroit locker in the 14b could put that up closer to the $600-$800 range. However you're always buying a pig in a poke with things like this. You would have to remove the covers and verify you're getting what you pay for, then you gotta hope the locker(s) aren't worn out and that the gears were set up properly. If everything is perfect and as advertised I could see the pair sell for $2,000 around here.