European & Asian buyers are very aggressive.

The Omega PloProf and Seamaster 600 / 1000M led the way.

The PloProf used to go for $1500 in 2003, and for a $450 service at Omega SA, it would come back new; they go for $9000 today

The Omega 1000M was always rare; sold around $3000-5000 in 2003; however it would not pass that ceiling given many would comment you could go out and buy a new Rolex Sea Dweller for that. There is one for $12,000 bid and another $18,000 BIN on ebay.

I think many have concluded on certain NOS / Grail / Cult models, if I dont buy this, it will be gone FOREVER....period.

Also, others will rationalize what they will spend an incremental few thousand on?:
-other generic modern watches,
-more mid-range filler watches to bulk the collection,
-2nd tier/used versions without NOS lustre
-or have watch-collecting inflation eat it till they find another....which may never happen.

Also, quality on ebay is a shadow of what it was 5yrs ago; so supply is vastly limited with demand expanding rapidly.

I personally learnt my lesson on a NOS Autavia GMT that i passed on for $1250 at Joseph-Gisbert weeks before 9/11. It was gone; 2 weeks later. 7 Years later have not seen another, at any price. I also passed on many PloProfs, and got 3-4 other divers for same total value, that today are 10-15% up from what i paid.

Lessons learned & not to be repeated!