Surely the cushioning can't be plain EVA with that durability? It can compress quite fast. Certainly when I've used shoes with it to walk to/from work on tarmac they've given up (painfully!) somewhere around the ~350 mile mark they're quoting as usual.
EVA is made in different densities and in this case, there are additional areas of what I'm thinking is probably some sort of PU, plus it all feels quite stiff to start with - some shoes I've seen compress easily from new with just thumb pressure, these don't. I'll try and get some more details from UK Gear.
The build quality and sophistication feels impressive too, solid and with state of the art looks - I guess what I'm saying is that the shoe feels like it uses modern, sophisiticated technologies, it's not some heavy, overbuilt behemoth of a thing.
The price, I would guess, is down to the use of decent materials, but given that 500 miles is a usual sort of estimate for the life of a pair of running shoes, I'd guess UK Gear would argue that the price is more than justified by increased life span.