I consider transport to and from a range and interstate (or even intrastate) transport to be two different circumstances requiring two different solutions. Truly, there is no such thing as "one size fits all" or one case fits all circumstances.
As for home storage, if one cannot afford a safe, it is relatively easy to turn a closet into a semi-secure storage area. Install two dead-bolt assemblies on the door, one about 24 inches from the bottom and the other about 24 inches from the top. Then instead of the usual two hinges, use four anti-removal hinges. These have pins on one half that mate into corresponding holes on the other half. Even if the hinge pins are removed, the door cannot be removed from the frame. Using a solid-core, rather than the usual hollow-core, door adds to the security.
While not a vault by any stretch of the imagination, it will provide a storage area that the kids or casual visitors cannot get into and will cost less than $100, not counting the cost of a solid-core door, which runs $50-$80.
Even if you have one of the cheapie Stack-On sheet metal gun cabinets, putting it in a secure closet makes another level of inaccessibility to your firearms.