These three listings seem like they have the potential be good deals... if you're in the market for a keyboard that requires some work.
IBM Model M 1390120 - According to the seller, it has an 'F9' key cap in place of 'F4' and has only been lightly tested. - Current bid $0.01 USD
IBM Model M 5-2 - Missing the down arrow key cap, "Guaranteed not to be DOA." - Buy it Now price $29.95 USD
IBM Model M 1391472 (Space Saving) - This one appears as though it just requires a thorough cleaning. - Buy it Now price $59.95 USD
As always, use caution while on eBay.
-Z