I managed to pick up an Apple Wireless Keyboard the other month for £40, and I've gotta say I'm chuffed with it. It has the same lovely soft keys as the Macbook, and an anodised aluminium finish of just a few mm thick. With the bluetooth keyboard market so empty right now, it's the only one I can really recommend. Only problem is it doesn't fold, and has no number pad, but it fits perfectly within a cm in the main pocket of my bag so it doesn't matter for me. Don't know how important a criteria folding is for you...