Well, there are many producers of foam army transport bags and boxes, which are all somewhat comparable in terms of quality.
Makers include but are not limited to feldherr, battlefoam or krmulticase.
Compare prices and pick what best fits your needs.
You could go to the next DIY store and look for a toolbox + soft foam and create your own. Last time I went to the DIY store though, premade transport solutions worked out to be cheaper.
Alternatively, so called 'bacon trays' made from metal can be used if you put magnets under the bases of your miniatures.
Another alternative would be tackle boxes (used to keep lures) from fishing shops or sorting boxes for beads from an arts and craft store. Finding one with compartments of the right size can be hard though and some sort of padding might be required.
edit:
D'oh - just saw all of this is already mentioned in the other thread on storage and transport:
https://bg.battletech.com/forums/index.php?topic=61698.0