The first over-the-counter birth control pill will be available on pharmacy and store shelves nationwide and online later this month, and will cost about $20 for a 30-day supply, Perrigo, its manufacturer announced on Monday.Now available for pre-order from some online retailers, the product, Opill, was approved by the U.S. Food and Drug Administration for OTC use for all ages in July, making it the first daily birth control cleared for sale without a prescription in the U.S. The product will come in a variety of sizes, including one-month three-month and six-month packs, with suggested…