Not “better”, but rare. Supply demand.
See example:
https://www.carousell.sg/p/rolex-5513-“pcg”-gilt-underline-submariner-1137189540/?t-id=mGluC_XLve_1644136117759&t-referrer_browse_type=search_results&t-referrer_request_id=dB5ne-d4-b0DQfuR&t-referrer_search_query=Rolex gilt&t-referrer_sort_by=popular&t-tap_index=1
What is “reasonable”? In 2006, you could’ve walked into an AD bought a sea dweller at a discount.
If you really want a 2006 sea dweller, simply research all the sea dwellers of that period to see which ones are good value. If you want to buy for “investment”, I’d only go for full sets, but those in turn will command a premium. You’ll earn it back and much more when you sell in 20 years.
But know that buying older Rolexes can be a minefield. You need to really do your research and know what bracelets belong to what watch, know how to spot service replacement parts…etc.
For a 2006 era watch, it’s still pretty safe. But when you go older like 80/70/60’s, you really gotta know you stuff.