The Great lakes can be probably be done more cheaply than any other big water. If you can get by without electricity you can rent a bouy or ball at many marinas for around $500 a year. Or get a trailerable boat (which I DO NOT recommend). Shop around for a cheaper marina, buy a reasonable sized boat and get on the water.
Your biggest expense will probably be in the making of the boat your own. Adding the accessories you want, (radar, gps, fishing gear, etc) You can do this pretty cheap too, Go with used equip or none at all to start. Buy a decent boat with good bones but you don't need a K.K. or a show boat.
Some people "Co-Op" a boat ( not recommended)
Go for it.
pete