This Microsoft Universal Keyboard drops from $79.95 to $39.95 at the Microsoft Store. Plus, the shipping is free. This is the lowest price we could find for one of these Bluetooth keyboards by $7. It has a six-hour battery life and is compatible with the iPad Air 1/2, iPad Mini 1/2, Android tablets, the Microsoft Surface Pro 3, Windows tablets, and Android phones or iPhones. Sales tax is charged in most states.