having owned a 18 tahiti they're a great starter boat. they're quarter stringer and have some decent flex in the hull. you can strengthen the deck and dash with a bulkhead. doing mid 60s is common, and anything beyond that with some decent power you're better off at other hulls. just depends on what your expectations and hopes are in a boat. as with anything go over it with a fine tooth comb. you mentioned nothing about the stringer and floor condition. make sure you tap everywhere with a hammer or something solid and check for rot/water damage. you should be expecting to pay under $5k for a perfect runner.