Regal’s small popcorn costs the equivalent of 6.5 cents an ounce, which is actually a bargain compared with its competitors National Amusements’ Showcase Cinemas (9 cents an ounce), Landmark’s Kendall Square theater (8.7 cents an ounce), F.E.I. Theaters (7.8 cents), and AMC Entertainment Inc. (7.5 cents).