Wrong and wrong. Nintendo doesn't sell them, but "flashcarts" do exist. Even better, most of them take regular MicroSD and MicroSDHC memory cards - thus requiring no specialist hardware beyond an SD (or SDHC) card reader.
There actually is a DOS emulator for it, too:
http://dsx86.patrickaalto.com/. If you decide to invest in a SuperCard DS Two, there's a version of DSx86 designed specifically to take advantage of that card's extra RAM and procesing power.
The only problem would be if you have a 3DS or DSi, as those are much heavier on security (DS Phat / DS Lite are OK).
PS. If you could do me a small favor, try using
this to manage your DSx86 configuration profiles and let me know what you think of it.
