Supplies of such things seem to be dry at the moment. I checked a few resellers who sometimes have them. Nothing. Apple only has a black refurb which is a discount off the original price but more than you need. The stock at the Apple online store does change daily, though, so they could get one at any time. But, there aren't likely to be too many last generation refurbs at this point, it seems, more likely current generation which won't give you much of a discount.

Could I interest you in a well used a 12" PowerBook G4 867MHz?