I remember looking at them, and between the cost, size issues, etc. they just didn't fit my needs.
The metal socket rails were OK, but I found the clips eventually became loose, bent and didn't hold as well. Those old trays like Elroy's, didn't have socket rails and fit what came in them. We used to have a place that had a bunch of them, but they didn't fit what I needed, and I didn't have metal to make any.
Then I found the plastic rails that have been made here and over there. The USA ones I saw locally, were shorter then the ones at HF and they are only rails. Kind of like the tool box thing, I would rather spend less on storage, and more on the tools. The plastic ones tend to lock the sockets better, so I started with them in my portable/vehicle tool box.