I was impressed with one of the new Gretsch ones I tried (it had the spider bridge....not sure what they call that one). MM don't do a wood body.
If you go nationalguitar.com (not nationalguitarS.com) you'll get to a site that sells a line called Hot Rod - they do what appears to be a great sounding wood body reso. They're in the US but you could probably still get one shipped for £500.
Dobro has indeed become a generic term, but it refers to the style of cone/brodge assembly as opposed to the body material. "Dobros" have a "spider" bridge - the bridge sits on legs that extend to the edges of the (outward-facing) cone and transfer string vobration from the edge of the cone. They have that nasal country slide sound. The other main types of reso work by transferring string vibration from the centre of an inward facing cone (or cones).
I played one of these today and the guy will put it in a hard case for £425. The only thing I didn't like was the finish which was sort of relic'd.
I am going to ask if he will do the shiny finish one for the same price but he would have to bring it in.