These natural enemies of fire ants are not commercially available. You will not need to purchase them because the natural enemies are expected to spread on their own. It would be too expensive for the typical homeowner to purchase the natural enemies, even if the enemies were commercially available.
For example, it costs several thousand dollars to get a decapitating fly population started in a particular area. Phorid flies in the genus Pseudacteon, also called decapitating flies, and Kneallhazia, a fungus, have been released in most southern states. These natural enemies have spread rapidly from the point of release.
Find more information about fire ants in eXtension's Imported Fire Ant Resource Area.