BoxWave Corporation via Amazon offers the BoxWave Almost Nothing Case for iPhone 6 Plus for $9.95. Coupon code "PGF7ZMXI" cuts it to $1. With $2 for shipping, that's $9 off and a very low price for an iPhone 6 Plus Case.
Of note, this case is currently out-of-stock but it can still be ordered. It's listed as being back in stock on October 10.