Well, I honestly wish you could buy these things at bestbuy, but the answer is No.
These are rather shady devices with two sides to them. The one side that we all want to think is it's only "true" purpose, is to run emulators, movies, picture viewers, and other great homebrew software.
The flip side of things is, Yes, you can bust out gba roms and the like on it.
What I have done is backed up all my gba games in my DS bag, and compiled them into just 1 cart, my Xrom 512, to help me with cutting down my cargo of time-killers in my backpack.
You can find more info on the Xrom, and how to buy it here:
http://www.gameboy-advance.net/flash_card/gba_X-ROM.htm
It's 84 bux, a little under 100 with shipping.
This device requires a GBA or SP to run, as it uses the old multiplayer link port to tap into the gba's cartridge port via the "hold start + select" boot sequence that sets the gba into a single cart slave awaiting for a multiboot header.
I'm still working out the kinks with getting all this homebrew stuff to work, but overall, I'm very pleased.