I like a lot of the suggestions above including the Longines but I thought I would offer less expensive alternatives based on your favourite four watches above. 1. Rolex...I don't think you will find anything really close to the deepsea other than the deepsea itself. However, as mentioned above Tudor is the closest thing to Rolex without being a Rolex. The Black Bay or Pelagos (if you actually dive) are both solid choices and despite the standard movements, their popularity should guarantee they hold their value really well. 2. Fusion - I would look at the IWC Ingenieur 3227. Might be a bit tough to get under that 4k limit but you could get very close. 3. Blancpain - Breitling Superocean Heritage Chrono looks very similar from a quality watchmaker - grey market pricing around 4200. 4. Seamaster 300 - how about an original SM300? The vintage models will probably increase in value. There is a caveat here is that it might be difficult to find and verify a truly original. Other? Omega PO 8500. Arguably the only diver with an inhouse movement you can get at this price (not counting Nomos).