You can buy an old Sunfish (13 feet) with 75 foot sail complete for $500 nearly anywhere. It is a good sailing platform to learn on and is simple to rig and maintain.
Talk to the folks at your local clubs and see what they use for trainers or round the buoy dinghy
racers and see if they have some cast offs.
Your hull is going to require lots of things and the prices quoted by Ex-Calif to get it sailing properly might be a little high but not totally out of line. You might be able to scavange enough to put it together but you can't count on that.
Good luck on your project
. At $60 I would probably have bought it too but I have all kinds of spare parts here to put a dinghy together.