I bought mine at:
http://www.filmsas.nl/catalog/index.php?manufacturers_id=19&osCsid=f0fc8679cc8d9f51c18eac4c87010d62
it's in the Netherlands, Europe, probably not much of use when you're on the other side of the ocean.. The EMS-cases are nice, tight cases.. I cannot compare them to other brands that make ABS-flightcases.. I don't know if they would survive a flight on a plane, but it never was my intention to take them on a plane anyway.. I chose them because of the formfactor, and the idea of modularity appealed to me.. If I would need to expand in the future, that's possible by just adding higher side panels, but you allready knew that.
Good luck..
there's a picture of my EMS-cart on Jef's soundcart-gallery