Welcome. I would stay in the 16-22ft range to start off in and learn in. There are plenty of small boats like that around for well under 6k. Look around the lake and see what others are sailing, also its a great idea if there is a sailing club in your area to go down and just start talking . If they do racing everyone is looking for crew and you should be able to get on a boat and LEARN. You will learn what you don't know and then some. You will also get a feel for what you might want in a boat. Have fun sailing is addictive!