Are all USB numeric keypads OSX comatible? My office uses the small Apple bluetooth keyboards.  I have a user who is requesting a numeric keypad.  Apple sells a Belkin wireless keypad on their website, but it has terrible reviews and it isnt cheap.  

There are countless USB numeric keypads that are a fraction of the price, all designed for Windows.  

If I buy one of the USB ones, it should work on a Mac, right?  It is just a USB keyboard...
Yes, if it's just a normal keyboard input device, which it should be.
I have one which doesn't say it's specifically for OS X, but works fine—it's just a keyboard.