I completely agree.
My wife's wireless keyboard will usually let me access BIOS, but sometimes it won't...
You don't have to spend a lot, as Patio suggests -- in fact, I've had advanced keyboards that plug into the PS/2 port or the USB port, but they Windows - driven: they rely on the operating system itself to drive the keyboard, so you're still stuck if you're trying to access the computer at a point where the operating system loads.
A basic keyboard in the price range should work just fine.