There are a few out there. If you're looking at them, check for contact information. If it's of non UK origin, I'd be very wary.
BM dresses seem to be hideously costly for what they are when you get up close to them, especially those sold through bridal shops.
I'm only having one BM and said effectively that she could wear anything she wanted, so it wasn't so difficult as having lots of BM's of different ages/shapes. What I did think was that keeping styles, fabrics etc very simple looked better. Have you thought about multiway dresses? Twobirds do a short version.
My BM has picked dark blue like the two you posted. Hopefully this will be an easy colour to mix and match.
Only a week and a half to go now and thoroughly enjoyed the planning. Very best wishes to you for a happy run up to your wedding, Kitty