The last watch on this list is definitely going to be the most controversial pick. Nautilus madness has in turn sparked Aquanaut madness, and now these less popular sport watches are nearly impossible to get at retail. If you want one, you’re likely paying 1.5-2x retail on the grey market or from a private dealer. Personally, I’ve always preferred the older Aquanaut models, and this special blue model, made exclusively for the Japanese market, is a longtime favorite. The smaller 36mm size, the less flashy dial, and the more flexible rubber strap make the 5066 a winner, and here you might be able to snag this rare variant for less than a modern 5167A. So, yeah, close to $50k for a steel Aquanaut (and I do think the price will end up somewhere around there), but at least here you’re getting something genuinely special for your shekels. 

This watch is Lot 120, and it carries an estimate of $20,700-$41,300.