Make sure the hull is in good repair. There should be no evidence of significant cracks in important areas, like where the centerboard trunk meets the hull. The rudder pintles shouldn't be loose and the rudder should be in good repair. Examine the centerboard, it should be present and as it is steel, not a sheet of rust. If you get a chance to sail, verify that it can be lowered and raised.
From one ad I read it said that the hull will plane, if true it will be fast for a sailboat. It also has a nice little cabin.
Good luck. That is a great price.
Bob
In some ways the boat is the least of your troubles. Much of the value of a small boat is in how good the trailer, the sails and the outboard are. The outboard should not be started without a water source for the water pump. If you can start it, pay attention to whether it starts readily and idles well. If it is a two stroke expect it to smoke a bit. The trailer should be in good repair. Look for dry rot in the tire side walls, check if the lights are functional and for structural damage (rot, rust). If it has wood bunks or rollers check to see if they need replacing. Pull out the sails. If they are newer they will be stiff and crisp. If they are older they will be soft and thin. Look at the stitching. If it seems to be coming out in spots the sails may need some attention. Look for chafing at about spreader height on the main and jib. Make sure all the attachment points are serviceable at the corners of each sail.