Buy Nintendo 3DS R4 Flash Cards for playing game backup copies (DS and 3DS ROMs)»
It will now be possible for you to purchase the latest game cartridges for the 3DS at a game store which already has one game on it most of the time, but if you get lucky, you may also get a chance to purchase one that has 2 games already. What you will surely be more interested in would be the multi-game cartridges for the 3DS which can store the game backups, and this is called the 3DS roms which you will find on a very affordable microSD card. Download 3DS ROM Games .
This will allow you to play with different 3DS games for free which can be downloaded over the Internet with just one cartridge, without even swapping game cards whenever you feel like playing another game.