You can try luvmybetta.com <--- just recently got a pair from her, bluebettausa.com(better selection) and betterbettas.com(ok selection). I think you will be able to find what you want if u try either bluebettausa or luvmybetta.
i was wonder, like i saw these food thing where it said feeds betta for up to 7 days, then i saw this rock thing that fizzes, would it be possible to put that in the water and send it through regular mail ??
You actually fast a betta for at least 24 hours before shipping. They can go two weeks without food, but ammonia builds up very quickly in the small amount of water they are shipped in, so you want them pooing as little as possible. A food cube would definitely result in a dead betta.