Emulators/ROMs are currently unavailable online. In fact, to my knowledge there is no 3DS titles available on PC, as no one has gone viral about how to access the hidden data of the 3DS. (In order to make ROMs and emulators, you need the hidden data of a game.)
Anyway, emulators and ROMs are never that good, since there always has to be one glitch in the game, somewhere, somehow.
But yeah, there are no 3DS titles available on the PC so far. So, I'd recommend just buying a 3DS. It may cost a lot, but it'll be worth it considering how many good titles are available on the console.
Hope I helped. :)