Charter Boat purchasing
I know this is not what you are asking for but Cruising World (I think) did an article on the pros and cons of buying a new boat and putting into charter. The problem I see is that an average charter boat probably sees 40 (?) weeks of use per year. In addition, they are subjected to the heat and damaging effects of a tropical sun (typically). So, the chronologically 2 year old boat you are buying has the wear of a 5-7 year old boat. As such, they may seem cheap at first blush but really have had the salt taken out of them thru use and the weather. As for resale value, I would say that any knowledgeable buyer will ask if the boat has been in charter and take an appropriate discount.