There are so many things to look for when buying a boat, but insisting on a test ride goes a long way for someone who doesn't know much about boats. If the seller is reluctant to do that for say $50-100 I'd pass. Do all the gauges work? Often some will and some won't. Does the battery sound strong, and is there a second battery if it comes with a big stereo? If it has a floor is it soft anywhere (be sure you check). Check any stringers you can see (be careful for violent reaction when you break out a small hammer LOL) Do the plugs, wires, alum manifolds look crusty? Any signs of leaks around the motor?
Don't forget the trailer inspection. Very important to check the date codes on the tires. Trailer tires are frequently 10 years old and don't show it but still remain sketchy in my book. Use it as leverage on the price. A trailer rehab can run $1k easy. If there is an old crusty nylon strap or rope instead of cable holding the front of your boat down, I'd damn sure replace that too. Trailer failures can be ugly as hell, and people can die. Don't be that guy. The worst thing that happens when your boat fails is that you float back to camp.
Depending where you are located, I'm sure there are a few good folks around here who would be glad to come along and give you a second set of eyes on a potential purchase. And there are so many open bows for sale right now that I'm sure you can find one in your price range.
