I've made a few raffle quilts. If you live in a sports-oriented area these are big winners. I'm not far from Pittsburgh and the 2 Steeler quilts I made sold tons of tickets. (Around here you can paint a rock black and gold and sell it LOL). I prefer to piece my quilts myself because it's all I can do to get my own blocks the same size. I'm afraid if I tried to work with others blocks I wouldn't get them to match up.
As Prism suggested, leave time to sell tickets; also have the quilt in a highly visible area and move it around the area. Get permission from a mall or grocery store or discount store to set up a table and display and sell tickets. Most are willing to let you do this for a few hours at a time.
Good luck to you and your friends.