You should consider getting cloud backup, or, at least, keeping one of the sets of masters somewhere other than your house. The data gurus at work say (minimum) three copies, with (minimum) one off-site. I really like iDrive and I know others here speak highly of Hightail and Backblaze.
As for SD cases,
this one looks pretty cool (sorry link is in Dutch). Only forty slots, though. Pelican makes a really nice one, but pretty pricey and even less room for cards.