Grainger price (not logged in) shows as $242.50. Ebay shows them for $75 to $180.
I got 4 of them along with 3 12 volt cart motors and a 24 volt gear motor (RPM unknown, but I may have an immediate use for) the other day for $40 total. The guy said he just wanted to get rid of them and start with motors built for the purpose for his application. (Building a CNC plasma table) I can see one reason right off the bat he might not have wanted to use them. They are single shaft. He would have had to mount his encoder somewhere other than on the convenient back shaft like one might on a purpose built servo motor.
My thought was just that I got $500 + worth of motors for $40. I also considered using them myself if I convert the RF-30 to CNC. The problem is of course chasing down or building a 90VDC power supply that doesn't cost so much as to invalidate the savings on the motors.
I unwound the transformer on the Hurco and I am running it at 78 volts to stay within spec on my servo controllers. I suspect these would run fin on78-80 volts if I wanted to use one for a second spindle lift or 4th axis table or even as a knee lift. I might have to add some more capacitance though. Anyway. I do have a power supply to test them on.