Enough of the options, what about a solution?

After lots of research and some trials/errors, here's what ended up being important:

- flexible compartment sizes
- latched boxes providing some level of portability
- individual slots so that a single-level could be accessed
- reasonably price

With all the options out there, the Raaco HandyBox is the only company and design that I could find that meets the need. Raaco is a UK company and it seems that distribution in the U.S. is limited. Most suppliers have the "professional" version for about $125. But Newark/Element14 sells a "standard" unit version (rack, 4 boxes and a variety of inserts) for 75 each plus $10 for shipping. Buy 2 or more and shipping is free.

The price feels high compared to other options but it is actually a middle of the road option with a per compartment cost of $0.65 ($20 per box with maximum of 32 compartments per box).