I’ll ultimately add a nice 1675 like Blaise’s to my stable, but I’m happy I went down the more esoteric path with the Rolex GMT Master 16753. It’s truly a different kind of watch that’s packed with a great, convenient movement and the same “toolish” features that make the stainless versions a favorite. Plus, prices are lower than 1675’s, the Root Beers are easier to source and you can be assured that you’re sporting a less seen, likely more rare, timepiece. Now, if anyone has a gold 1980’s Mercedes 560SEC for sale, I think my look will be complete.
In the UK, the retail price for the stainless steel 'Pilots' range (such as the GMT Master II ) starts from GBP5,600. Diamond inlay watches are more expensive. The book " Vintage Wristwatches " by Antiques Roadshow 's Reyne Haines listed a price estimate of vintage Rolex watches that ranged between US$650 and US$75,000, while listing vintage Tudors between US$250 and US$9,000.  The most expensive Rolex ever produced by the Rolex factory was the GMT Ice reference 116769TBR with a retail price of US$485,350. A Forbes magazine article on the Swiss watch industry compared the retail value of Rolexes to that of competing brands Corum , Universal Genève and IWC . 
As mentioned in an earlier comment, I do not believe, the gold or two-tone GMTs (by the way:not GMT’s…) with ref 16758 deserve the steady mentionning of tastefully doubtful periods, especially as they are still nice successors of the 1675, which are, in my opinion, the “real thing” and have their roots in the sixties. Not to speak of the 6542s, the prices of which, especially with the original radium dials, have, long ago, escaped the possibiilities of common mortals.
I do, however appreciate very much your efforts to draw the attention of your readers towards watches like GMTs, day-dates and turn-o-graphs, which are, to some extent, been in the shadow of their “sportier” siblings and deserve our attention.