The people who are showing their crafts and artwork at the craft show may be willing to give away some of their works for free, especially if they get a discount on their booth rental fee. You'll have a variety of items to choose from, which is perfect for giving away multiple prizes. Try to get a piece of jewelry from one of the show's jewelry makers, a painting or print of a work from a painter, and other tangible items that can be shown. If people can see the goods that they could win, they are far more likely to buy a raffle ticket. Don't neglect the intangibles, though. A photo session with one of the show's photographers is also a quality prize.
Instead of giving away large prizes, ask the artists for smaller items and combine several of them together into gift baskets. This takes some of the burden off of the artists to provide one large item, which may normally sell for hundreds of dollars, and may increase interest in the raffle. With the variety of items in a gift basket, you may draw in people who would otherwise not participate, because there is a better chance of them winning at least one thing that they like.
People will enter the raffle for gift certificates to just about anywhere, but try to keep it about the art. Some of the people in attendance at the art show will certainly be artists themselves. Gift certificates to art and crafts stores like Hobby Lobby or Michael's may appeal to these people. At the very least, it will appeal to the artists at your show.
You can also give away a gift certificate to be spent at the show. The winner can use the certificate to shop at any booth or combination of booths, the money is tracked, and you can then pay the artists whose work was purchased using the certificate. With this prize, the winner benefits from the free items and the artists benefit from additional sales.