buy a black bay on the used market ~$2500, (essentially new $1000 -$1500 off retail) youre looking at 20-30 years for ROI.
dont think they'll go much cheaper than this and will only increase from that plateau price.
that ceramic no date sub is not special enough, all it has going for it is the word rolex on the dial (yeah, im sure the movement is great)
on the second hand market theyre not much of a discount
look at the resale value of the 14060 maybe +$1000 return from 20 years ago, they can be had for $3500-$4500 two line NON COSC
so maybe buy a vintage no date sub, 14060 which will also continue to increase in price as it becomes a quaint tool watch compared to the bulky ceramic bezel no date sub. the 14060 is this generations plastic dome 5513
its value will probably out pace a black bay, but buying a used tudor BB wouldnt be a bad choice either, as i said, great classic style, great value int he long term will hold its value and increase