Follow up
 

I sent another email to Sig Sauer headquarters asking if this could be an accessory from the 1994-95 time period. I just this morning received a reply. It read "We have no information on them. I would check with Buck".

I'll run it by Joe Houser at Buck and see if he can shed any light on the situation. I seriously doubt that Buck would have produced an M9 bayonet with the Phrobis name on it.

M9 SIG markings
 

I think it is interesting that there was no last minute/second biddings. The bayonet reached the $580 mark fairly fast and normally when an item reaches that price, that fast you have last minute bids that take it a hundred or two higher. This might indicate that those bidding may have read these threads and wised up. Might have saved somebody a lot of money!

Yes, perhaps. Now the big question, will the buyer fess up to it? Who bought the SIG M9?