I picked up a Logitech PS2 USB headset for $10 and it works very well. I don't like the way the pad presses against my ear, but the microphone is nice enough that I don't have to wear the headset normally for it to work and since it's USB, it's plug and play so you can easily use it on your PS3 and computer.
I had a Skype chat with some friends and I laid the headset down on my desk and despite being a foot or so in front of my speakers, the mic input meter on Skype never showed it picking up the other people in the chat. When playing on the PS3, I popped in Killzone 2 and cranked up the speakers (something I could NEVER do with a regular bluetooth headset) and it didn't pick up any sounds from the game (as noted by not seeing my name pop up on screen).
This is what it looks like. The thing that worries me is how thin the band that goes over your head is.
http://www.ioffer.com/img/item/582/741/06/weJuNcFlqvK9sct.jpg
