I'd say you could hope for $50, tops, if they're still in really good shape with no visible markings on the teeth, and if they're a quality brand (FRPP, mainly). As stated, most folks are really wary of used gears because you can't always tell at a glance how good/bad they might be once installed, and because it's a major PITA to have to swap them out again if/when they fail.
Ain't that the truth. This is a little off topic but related...
I had a brand new set of FRPP 3.73s installed along with all new bearings, cups and seals for $325 at a reputable shop. As soon as I took the car for a drive the gears were whining and I took it right back and complained. The shop owner said it was normal for a little whine. I argued that Ford installed literally tens of millions of gear sets in 8.8s without them making any noise. He refused to look at the rear any further.
About a year later I started hearing a strange noise in the left rear brake right as I came to a stop. I pulled the wheel and the axle seal (which the shop had replaced) was leaking already. I have also noticed that the rear is "clunking" now.
Since it's been 2 years now and I have another brand new set of 3.73s that a local NC shop will install for $250.
The point is that everything has to be right with rear gears or it will eventually fail.
Ain't that the truth. This is a little off topic but related...
I had a brand new set of FRPP 3.73s installed along with all new bearings, cups and seals for $325 at a reputable shop. As soon as I took the car for a drive the gears were whining and I took it right back and complained. The shop owner said it was normal for a little whine. I argued that Ford installed literally tens of millions of gear sets in 8.8s without them making any noise. He refused to look at the rear any further.
About a year later I started hearing a strange noise in the left rear brake right as I came to a stop. I pulled the wheel and the axle seal (which the shop had replaced) was leaking already. I have also noticed that the rear is "clunking" now.
Since it's been 2 years now and I have another brand new set of 3.73s that a local NC shop will install for $250.
The point is that everything has to be right with rear gears or it will eventually fail.
this is the reason why I bought the whole FRPP axle assembly brand new with seals bearings installed, 373's, trac-loc. Just throw your axles in and go. It was like 900 bucks shipped from mustangs unlimited. took me all of about 3 hours to install. looks nice too.