SandStorm Productions sells a large selection of Star Wars masks, props, costumes, and so on. They even have auctions for homemade items. I've got new information on FutureHorizons. Please see the FAQ for the new information . Sabers U.K. has a great selection of saber, hilt, and plasma replicas and kits.
Icons makes expensive but perfect replicas of many movie-related props.
This site sells Icons prop replicas. These have been advertised in various magazines for a while. These are wonderful, virtually exact reproductions, but not for the small of budget. Visit these excellent Collectors Empire sites dedicated to prop replicas. These are reasonable alternatives to the Collectors Gallery, but I still think you would get more enjoyment out of building your own.