The Supermicro CSE-M35T or M35TQ 5-in-3 hotswap adapters are built like a tank, and 3 of them makes a great 15-drive tower out of an Antec 900 case, or four in an Antec 1200 case for 20 drives! (I've done those builds a few times for friends and other forum members!)
The original list on these is something like $220 each, and the prices on ebay which look like $75-95 each shipped are the lowest I have ever seen, so I doubt you will do significantly better unless someone local has some to dump. For some reason Newegg has them for only $90 each right now actually!
Be aware that any 5-in-3 adapter requires you to bend down two sets of 5.25" drive supports with pliers or clamps or something - there wouldn't be enough room for drives if they were cut in for clearance. Lower density adapters 4-in-3 and 3-in-2 have grooves and do not require case mods.
IcyDock has variable build / design quality, but nothing I have seen is as good as the Supermicro adpaters. My favorite trayless adapters are the iStarUSA ones, and sometimes Newegg has those on super sale, I think $50 for the 4-in-3 after rebate on black Friday once. Typically the 5-in-3 are $100-120 and they don't tend to go on sale as much.
Good luck!
