When I had my last boat for sale one of the most common questions was "Do you have a survey?"
As a survey is required every five years in our area by insurance company and is one of the first things you have to do after buying a boat most boats typically have a survey 5 years old or less.
Since these are not for selling purposes but for valuation purposes they are for the new owner's benefit. It usually states condition of hull, rigging and age of equipment and sails, instrumentation and if it is working. teh ones I had done were pretty basic but do list age and condition of sails, instruments and deck moisture information (listed moisture around chainplates and cockpit floor).
When I decided to sell my last boat I scanned the old survey (was dated after all) and provided a link. If noting else it listed deficiencies I was informed of at time of purchase which could be compared against the work that was performed over the time of ownership.
A good starting place before taking the trip to look at the boat I guess.