Hi - Do you have any information on the overdrive ratio? That will be important, also, which model of the casale that you have will also make a difference. Is the case polished, are the gears and bearings in good shape? Oil changed often? What size HP were you running to it?
To give you an idea, I just spent $2300 to have my v-drive gone through. It needed new 49% overdrive gears, bearings and some other stuff. Wilkes recommended changing the oil often to save the wear and tear on the gears and bearings. I'm also running a gentry system, where the boat has made numerous hard starts, so the gears were showing wear when I opened up the case to see what I had.
Anyway - value will depend on the condition and what you have that meets the buyers needs. I would recommend that any used V-drive (or motor for that matter), be gone through and freshened up - that way you know what you have. Wilkes did my work for me, it felt smooth to me when I was installing the V-drive the other day. I'll know better when I get my motor installed next month and up and running. Seems like a lot, but the idea of puking gears through a casale case doesn't seem like much fun if the stuff comes apart. Just my thoughts though.