I got 2 bumpers with metal buttons on ebay for $9...one of them, the volume button didn't respond and the other bumper was bent a little and fit a little weird. Also, they are the exact same thickness as 4s style bumpers where as the Monoprice bumper I have is perfectly thin and can tell were made for the 5.
It I can have the Monoprice bumper with metal buttons, I'd be thrilled