I'd like to recommend you an affordable, safe and secure way to store your knife collection, that I use.
It is labeled as a gun case, but is perfectly suitable for knife storage.
The case is made from hard plastic, has a seal to protect from humidity, has double clasp and can be locked using a regular U lock.
But the best part of it is the Pick n Pluck Foam (just like in the Pelican cases) - so you can fit the cutout for each knife, and prevent unnecessary movement inside the case.
It fits for secure storage of up to 8 knives, 4 large ones (app. 4' blade) and 4 medium sized (3.5 inch blade and less).
The case is great for transporting several knives and to keep them secure inside the house - out of reach of children.
You can find it here: http://bit.ly/297Hbb7
This is how I arranged my case: