www.rackmountpro.com carries these, but they're $20/each and the shipping prices are horrendous.
They also carry one for an Athlon, which seems to work pretty well (for a 1U HSF on a Duron 1300...)
And not to contradict bigben2k, but it looks like it is skived, I know the Athlon ones we've got are, and the pic above certainly looks very similar.