Those are the same FETs that Robert Byrd uses at AtomicMods.com They are legit.
The FETs themselves don't have a heatsink on them, however, a heatsink making contact with the FETs would aid cooling them. However, you'll generally have to cut the heatsink to make room for the FET stack at x3 or x4 stack.
Anyway, why go through ebay? Goto
www.digikey.com and order them direct, probably cheaper too.