After a minor incident involving our dog and the post being delivered,
the internal letter plate on our front door has become detached.

It looks like I'll have to buy a complete new unit, as the plastic
torsion bars (if that's the correct term) which attach the plate to the
frame have snapped.

You'd think it'd be easy to buy a new one, but all the ones I can find
have a black pastic surround (e.g.
http://www.screwfix.com/app/sfd/cat/pro.jsp?id=17381)

I've tried the major DIY stores (i.e. B&Q, Homebase, Wickes), but they
all appear to stock something similar to that above, and for an
extortionate price.

Can anyone suggest somewhere that will sell me one with a gold-coloured
frame for a reasonable sum?