As of March 2015, games for the older Game Boy systems are commonly available on e-commerce sites such as Amazon and eBay. Games for the Game Boy Color and Game Boy Advance can be found through these sites as well.
Third-party sellers frequently sell games for all of the older Game Boy systems through Amazon.com and through eBay auctions. Some other sites where games for these systems can be found include Play-Asia, GameStop, Bonanza and Game Trading Zone. Games are also sometimes listed for sale on Craigslist, though it does not offer the levels of protection that other e-commerce sites offer for transactions by mail.