Shoptemp is good but the shipping is expensive due to having to ship from China. If you live in the US I would recommend realhotstuff instead. I think they still have free shipping but if not you will still save $10-$15 in shipping and it will get to you faster (shipped from New Jersey).
As for the DSTwo, it is an excellent choice. Though the GBA emulator isn't that good (about the same as the Dingoo/PSP one) DS games work great and the in game menu is far more compatible that my old CycloDS. So far, I haven't come across any games that will lock up if you use the in game menu or save states unlike the CycloDS where you had to be careful. For example, Chrono Trigger would lock up in battle, Final Fantasy 4 would lock up unless on the world/town/dungeon map (i.e. not in battle, in the menus, or in a cutscene), and Final Fantasy 12 would lock up anywhere with the in game menu on the CycloDS (Firmware 1.58) yet no problems on the DSTwo.