I think £185 is a little on the high side for a fairly basic 3-hander (although it could be fair). In any case I would only give it to somebody I had a firm recommendation for and I don't know whether that's the case with the high st watchmaker that you've mentioned. I think I'd be contacting one of the two Duncans (Genesis or The Watch Bloke) Rocco in Bristol (if he's not too busy and he always seems to be these days) or perhaps .Olli. (who has just done a lovely job on a pocket watch for me). I also use Rob Horan but he's in France and you don't want to go overseas.
Cousins do have some parts for your movement but, in the medium to long term, I'd also be looking to source a working donor watch from Ebay at the right price; Revue Thommen were fairly prolific and don't command any kind of a premium in the vintage market. With a bit of patience I'd say you'd get something around the £20 mark.
I think this is yours but pay attention to the jewel count.
http://www.ranfft.de/cgi-bin/bidfun-...swk&Revue_77_0