Considering that Luke Miani (YouTube channel) follows eBay values of various Macs pretty closely and recently picked up the "cheapest Mac Pro 2013 on eBay" for what he considered a very good deal (relatively speaking) of $1300— for a 6-core, 32GB, 256GB SSD, D300 config— I'd say $750 for a nearly maxed out 12-core model is one of the best deals you'll find currently. If it works and has no issues, $750 for a 12-core system actually makes it a decent value of computer, not just Mac Pro 2013 (unlike the overpriced new systems from Apple and their correspondingly overpriced used variants).