I bought the X31s on a brief sale at TRU for just over $60, otherwise they've always been a higher price as the OP and others here said. They're great wireless headphones for the money; although waiting for the X32x might not be a bad idea, with the larger sized speakers.
They don't have any kind of surround sound, but for basic headphones they work great. I think the microphone only works with the 360 (for chat) but these headphones should otherwise work with other platforms (PS3, PS, etc.).