I was immensely lucky to have picked up my "straight text" caseback 69ST Speedmaster when I did, and even more fortunate to have hung onto it! I wish I'd kept my racing dial MkII, which was lovely and tidy and about £1,500 from memory.
These days, I hanker after a Flightmaster and I'd love to have tried a vintage Heuer, maybe an Autavia GMT, but both these seem either to be incredibly expensive or really leggy and worn. I am still holding out for a Marine Chronometer or similar, though looking at the way those are appreciating I should probably crack on.