Modeled after the earlier KeyCover for iPad, Helium Digital's KeyCover Folio Keyboard Case for iPad mini ($60) is the least expensive iPad mini keyboard case to hit our office so far. Unlike the hard plastic iPad mini keyboard cases we've seen so far, this one is a faux leather folio, with chiclet-style keys inside the front cover. To accommodate the apostrophe key, which has been an issue on keyboards we've tested, Helium moved the colon/semicolon…