R4i Flash For Nintendo DSi

I bought a Nintendo DSi today and found out that the R4DS doesn't work with it. And so I began looking for answers and discovered that I need to use an R4i for the Nintendo DSi so I can upload and play flash cart games. Aside from the R4i, you can also use Acekard 2i. So now, I'm searching online where I can buy cheap R4i flash carts.