i know people like the DSTWO.....but guys....they are pretty much all gone, virtually all the reputable resellers are clean out of stock, and supercard aren't making any more
best advice is to just install the flashcard timewarp file to sysnand, make a nand backup first if your scared or something, but not 1 person has bricked their system by using flashcard time warp, i installed it on my n3DS even and it works fine.....and should you ever want to remove it, you can restore your original nand backup from the gateway menu
basically you will be able to use the blue card that came with your gateway in sysnand, so no additional purchases/flashcards needed and it takes like 1 minute to install