They are in all sorts of places now. You can try online retailers for products such as DVDs and other electronic goods, auction sites like Ebay, Yard sales and flea markets, etc.
You have a couple choices when it comes to used DVD's. You can go on Ebay and find just about any title you would want or another good place to get used Dvd's is at any Video store. The majority of them sell used Dvd's in order to have room for newer stock.
Many record stores which sell DVDs now have used sections. They are competing with online markets (which have thousands of used DVDs), so they have to try to accomodate the used DVD niche.
You can pick them up at second-hand shops, like Goodwill; as well as rummage/garage sales, church bazaars, Ebay, and local auctions. You can also find them at library book sales.
