You can get this Slim Profile 64GB Flash Drive on sale for $14.99 right now (reg. $19). It's an easy, cheap option to store files on the move, weighs six grams, and is USB 2.0-compatible and able to work with PCs, Macs, and a wide range of MP3 music players, if you still happen to have one of those. It also comes with a keychain, but it can be removed if you don't plan to carry it around all the time.
You can get this Slim Profile 64GB Flash Drive on sale for $14.99 right now (reg. $19), though prices may change at any time.