Where can I download iOS 8.x firmware / IPSW files for the iPhone 6 Plus?

The iPhone 6 Plus was released with iOS 8.0, a 5.5-inch Retina HD display and A8 processor. Apple's largest smartphone to date, the iPhone 6 Plus packs a larger battery than the iPhone 6 and features optical image stabilization. Here are links to the official IPSW files for the iPhone 6 Plus:

iPhone 6 Plus iOS 8.1.1: iPhone7,1_8.1.1_12B436_Restore.ipsw
iPhone 6 Plus iOS 8.1.0: iPhone7,1_8.1_12B411_Restore.ipsw
iPhone 6 Plus iOS 8.0.2: iPhone7,1_8.0.2_12A405_Restore.ipsw
iPhone 6 Plus iOS 8.0.1: iPhone7,1_8.0.1_12A402_Restore.ipsw
iPhone 6 Plus iOS 8.0.0: iPhone7,1_8.0_12A366_Restore.ipsw