AceKard 2i

Something about RAM. GBA goes in Slot 2. Slot 1 just doesn't like it/support the RAM or something.
My topic was more about "Help me get a good card", so that might have made a difference. iunno. Ask Fiel? xP

In the link you put:

Can be used as a Passme to boot from slot-2 flash carts. Run GBA games by using expand cart The Acekard 2 can be used as a passkey, so you can boot your slot2 flash carts with it.
AK2 also support 3in1 expansion cart. You can run gba games from MicroSD card directly.
*You need insert MicroSD card with OSMenu to use Passme function.
*Expansion cart sold separately.
*There is no Slot2 in DSi.

So I would assume there's a separate product I would need to purchase to perform this task. Rawr.

And Yeah, I would assume the fact that you were asking about WHERE to buy it is the warnable area, since the warez rule says

This infraction also applies to those that link to places where a user could learn how to obtain warez.