At 50% off? It's inventory clearance.
(Which is just as true a sale as anything else is, mind you.)
Based on the reports I've heard, Chainmail has been a hit or miss thing for retailers. Some retailers have done very well with it, but it's died on a lot of shelves.
I don't know the managers at any Game Keepers, but I've heard a lot of reports of them doing clearance sales on Chainmail inventory. As far as I can tell, it died in most of those stores.
As for us, it pretty much died here. We sell a couple of each individual fig to fans as it comes out, but we never managed to sell a copy of the rules to anyone and almost nobody plays the game around here. Some of that's our fault -- we had massive problems getting the game on its initial release -- and some of it (IMHO) is because Wizards had no real chance of national success competing directly with GW.
yours,