Price aside, it's actually easy. Just buy a micro-SD card and the right "accessory" (there are maybe only two worth buying) and it takes a few minutes. With the most popular accessory, you can also run any home brew .3ds files very easily.
It only gets hard if you want to play online, which means you need to do .CIA files, which becomes difficult (it also requires a new SD card). But if playing online isn't a priority, it's not even an issue.
It only gets hard if you want to play online, which means you need to do .CIA files, which becomes difficult (it also requires a new SD card). But if playing online isn't a priority, it's not even an issue.