Daytona for me...but not like this man. If you can afford that purchase then you can afford reversing the process...hell, at half those prices it's what I do. Buy the seller, not the watch si often repeated here.so:
1- Find a reputable seller like HQ in San Francisco or one of many well known ones...or a Rolex house that deals with second hand, or Torneau although half of the time they don't know what they have but at least are very legitimate...or if you want reach out to ALL of them and tell them what you're looking for. i.e "I want a vintage Daytona or extremely valuable Sub, Rolex. My budget is about 25G but will consider items within range that are "don't miss" opportunities. They will ask you a couple of questions: Paul Newman? Color Dial etc etc and then you forget about it and go have a drink and go on with your life and let them do their work for you. Then you consider what they are offering you knowing they are already vetoed, without worries, rather than finding something that looks shinny and asking anonymous people online if you should shell 25G on a specific watch based on pictures.
On that note, to verify the provenance and 100% authenticity of these vintage pieces it is not enough to go to Rolex...it requires an expert even within Rolex. I'd be surprised if they will give you a guarantee on a 25g purchase on a day visit, I would think they will need to keep the watch and make sure the right person is looking at it. This may take time, and I doubt your seller will accept the cost, or risk.