I believe you are referring to Game Boy Advance (GBA) cartridges.
I'm sure you can find those on Amazon, but beware, they are most likely out of production and have become since then a bit pricey.
Alternatively, even if it is frowned upon in this community, you can easily emulate them via a GBA Emulator.
Just look one up and download one on google or, if you have an android phone, go check your Apps menu in the Play Store, there are literally tons of free emulators.
If you CAN'T find a legitimate copy of the game thru internet, emulating is your best bet.
Hope this helps!