First stop, http://chronomaddox.com/c1045_in_detail.html Get to know the line, the reference numbers, etc. Then searching will be easy. There should be one or two on ebay right now.
Tough to trust you'll find them all by searching only the reference number. On one hand, a seller who knows the reference number may be better able to describe the watch. On the other hand, you might miss the listing where the nephew knows only "old Omega" and nothing of the reference! These are great models, one of my favorites. Quite comfortable but very tall. The watch or the door jambs may need to be refinished in time...