Thing of the deep always sells fast for me, I've found three and they go very quick. Usually priced at 300-500K, Also rings and amulets go fairly quick. I can't sell a 1000+ dps bow at all, so I grind em into salvage or sell to vendor.
For armor to sell it needs very high str, ar, chc, chd and ias and sometimes vit. But still hit and miss.
What sells best for others, And rmah vs gah?