what about water balast ?
You might specify where and how you want to use your boat. Macs are light construction boats perhaps most suited for smaller lake use. If you want to sail on open water areas, consider a more strongly built boat. A S2 7.9 is a favorite of mine.
Figure out what you want and then pay the cost to get a good example, skip the search for any bargain boats - the most you can hope for in buying a boat is to get at least what you pay for.