Rjbergen’s list is an excellent outline. It also depends on your mechanical skills. My previous 4 boats were older under 21’ bow riders. Pretty easy to inspect myself. On our 280SSi for peace of mind we had a trusted dealership to handle the transaction. They did the paperwork, held the deposit contingent on survey, test ride and finance. I paid for the survey, previous owner paid for the minor things noted and dealership fee. When you look at the cost and complexity of engines, water systems, electronics, etc. unless I was 100% sure I’d walk away without the survey.