(FORTUNE Small Business) – Federal regulations require that hearing aids be custom-fitted by licensed audiologists, driving the average cost up to a pricey $2,200. Entrepreneur Mead Killion's firm, Etymotic Research, based in Elk Grove Village, Ill., says that it could develop a perfectly safe hearing aid priced at less than $300. Against entrenched opposition, Killion has petitioned the FDA to allow the devices to be sold over the counter in the U.S. --SHEREE R. CURRY