If you're talking about an encapsulated boat you're probably OK with 10 yrs. I've seen an outfitter in Pagosa that leaves their Maravias out all summer and they seem to be fine. If its just PVC I'd be wary of abrasions and pinhole leaks. Something else to consider with the age will be the condition of the D rings and other glued on accessories. With any used boat you'll need to air it up & give it a good look over. If its like you say, it sounds pretty cherry. PM me (or just ask here) if you want a reality check on the price.
Nothing in the world is more yielding and gentle than water. Yet it has no equal for conquering the resistant and tough. The flexible can overcome the unbending; the soft can overcome the hard. - Lao Tse