Woah $750 is an amazing deal on an iPad Pro with cellular. I'd say somewhere around 800-900 seems right for a barely used device with no damage.
[doublepost=1467757643][/doublepost]Also try posting on the Macrumors Marketplace
https://forums.macrumors.com/forums/marketplace.132/
Bought mine, with box (and clean iCloud, IMEI, etc) for $550. People want to get rid of these. That said, I listed it back on Craigslist (more for trade purposes - color) and have gotten a few offers in the $700 range. Maybe it's just your market.