Most of those stoves are cast with firebricks on the inside. Ever wonder why they all look virtually the same? Well most are coming in from China (nothing wrong with that) as the cost of setting up a 'cast' process is huge. The more novel (and pricier) tend to be Swedish/Norwegian (jotul for example) You are pretty much buying the exact same stuff, it's just branded differently.
for example, and as far as I'm aware, the only actual cast produced in the UK is here...dunsleyheat.co.uk excellent tertiary burn.
A great compromise is dowlingstoves.com. They are scottish, and build in thick mild steel to any size at a fairly competitive price (I think they were on CH4 kevin McClouds rand design a year or so ago, the modular steel house).
No fire bricks required, bespoke design, efficient burners.
personal recommendation, and no I don't work for them or get a slice of the action.
Make sure you add a Laddomat 21.