Sad, but true.
Gum arabic is essentially the hardened sap of Acacia Senegal trees. And by 'essentially', I mean 'precisely'. It ain't Bubble Yum, folks.
Sudan appears to be the primary exporter of gum arabic. The Gum Arabic Company, Ltd. has exclusive export rights in Sudan for, you guessed it, gum arabic. They claim to maintain 15,000 metric tons (or "tonnes") of gum arabic ready to ship out from Port Sudan, on the Red Sea, at all times.
P.L. Thomas and Co., Inc. is the exclusive agent of the Gum Arabic Company in North America, so contact them if you want to get your hands on some.
Along with xanthan gum, gum arabic is primarily used as an emulsifying agent in processed foods.