Raf,
you're right, there is nothing out there that limits the life of the airframe of a 172. Not that I can find, at least. However, with small airplanes I have a personal maximum of 6000 hrs simply because I felt I had to set a max. nevertheless, that does not mean that if an airplane was maintained properly it will fall apart beyond that number. A lot of airplanes that belong to comercial, or government agencies are maintained much better than all others primarily because pockets are deep and their insurance requires it. The most important thing to pay attention to is metal fatigue, or stress corrosion and such. Make sure the log books are complete and thorough. that there is history with replaced parts or upgraded systems. All certified parts should have a form known as an 8130 for repaired or a certified NEW document by an approved vendor for that type airplane. an airplane with 10000 hrs should have had at least 100 inspections and 5 ovehauls on the engine and propeller. I would make sure that the engine was re-manufactured instead of overhauled recently. I would not talk you out of this airplane right of the bat, but I would definetelly caution you to be very thorough...