I think that would be the normal procedure when buying a business. My brother in law ' Mario' had an icecream van and said - when it's good it's very good, when it's not it's hard work! You couldn't just suck it and see could you?
At 17.5k I would want every detail possible.. mind you, it's peanuts to some! I think just buying it and hoping would be a bit flakey!