I suggest you do some proper research before you get one.
They are the besterest animals on the face of the Earth, but you have to know what you are getting into. You cannot just "want" one. You should ensure that you are fully prepared for it before you even consider asking about where you can purchase one.
Be willing to give it 20 minutes undivided attention a day. Although they are commonly thought of as hardy pets, they are not such easy animals to care for.
I suggest you visit Dr. Caldwell's website.
For an eight gallon, Gonodactylellus viridis will work well, but they are relatively seclusive.
Neogonodactylus wennerae will work.
Gonodactylaceus glabrous will work.
Everyone will disagree with me, but I think you will be able to keep a G. chiragra in such a tank.
Please, PLEASE know what you are doing before you get one out of intuitive drive.
You will need a reliable source of live food (a beach, an lfs) and you might even need to set up a separate tank to house live food. You must feed a varied diet and live food.
Good Luck!
