The charger costs $59.99, and uses the Qi wireless charging standard, which means it's probably compatible with other devices too.
The charger looks pretty nice too, sort of like the defunct Nexus Q streaming TV device, but cut in half.
By the way, T-Mobile dropped the price of the Nexus 4 to $49 with a contract and mail-in rebate, so you may want to check that out too.