This came up recently with a friend whose son shares my son’s love of collecting DVDs and also his habit of being very hard on them, which can lead to much extra cost and emotional strain. Several years ago we bought a polishing machine, the same kind our local (and long gone) video rental store used. It has worked very well – we use it for movies, music CDs and computer games. It’s made in the U.S. but sold through a Quebec company through Amazon. It’s an investment, but in our experience it more than paid for itself, particularly for emergency repairs to a beloved-but-no-longer-playable DVD.
http://www.amazon.ca/JFJ-Easy-Universal-Repair-Machine/dp/B000RBE4B8
And yes, I know we should move into the digital world of on-line watching and digital copies, but our son values the physical existence of his DVDs. We value the fact that he makes a tangible purchase, which helps his understanding of money (he saves up to buy new releases on the precise date they come out). And his collection provides a valuable exercise in working on putting things in alphabetical order, a useful workplace skill.