buy acekard 2i in USA here: http://www.dsflashcart.com/
if you plan to buy acekard 2i card, i have a few suggestions for you, at first, you should buy a pre flashed one, if your DSi has been udated to V1.44. if you buy a non updated card, when you receive it, you will need to get a DS console to do the update, but not everyone has a ds console, and also not everyone know how to update acekard 2i with a DS console. so if you buy acekard 2i, just buy a pre updated one, many sellers provide this service, just check the description and confirm it before you buy it,
Another advice if you plan to buy acekard 2i, if you live in usa, it will be better you can buy from a US based acekard 2i seller, if you buy it from other contries, it will take about 15 days to arrive to usa, it is a long time and not always safe. but if you can buy it from usa, you will receive it in about 3 days, which will be very faster and easier.