I picked up a second band today from CEX to go along with my 42mm stainless steel. Got a black sports band, it's nice, doesn't feel like cheap rubber at all but I can tell I'm only going to use it every now and then as it does feel less "premium" than my milanese loop (obviously given the price difference). As for CEX they charged £45 and the strap was on its own, just the top part and a 'M/L' band, no second band of a different size or anything and no case. It looks like they're taking the bands off of traded in watches and selling them separate from the face.
Think I'll get a black leather loop when Apple do start shipping them (hopefully next month)