I frequently make and raffle off bed sized quilts for fundraising for our dog rescue. I sell chances at $10./each or 3 for $25.
Remember that it is a way for people to donate to charity, and have a chance at a prize- If it is a charity- make sure folks know that. Also, if it is a 501 (c) 3 charity, make sure they know that the donation is tax-deductible.