Going by trend, it's due to go on sale in 1-2 months, but Valve may try waiting until ~Christmas. Starting to accumulate a sizable Steam Wallet balance from just discovering I have a bunch of cards and TF2 crap and only just realizing there was a community marketplace... waiting for it to go on sale.
Fwiw, SGBTC has it at a discount over retail, but still >.02BTC.
http://steamgamesbtc.com/index.php?page=item&id=131Maybe give BTC price a day or two.