QUOTE(KTViola @ Jan 12 2009, 03:45 PM)

The biggest of the specialist musical instrument insurers usually want a valuation certificate from a reputable place if the instrument is worth more than a certain number of thousands.
Anything insured for 5k or above, I believe. You can insure it for your chosen amount in advance, pending a written valuation.
QUOTE
I second the recommendation for Guiviers if you're in London - they sold me a very nice viola last year and are friendly and unpretentious. Worth phoning or emailing them before you go though so that they have the right person ready to write up the description properly.

I bought a gold-mounted violin bow from them a few years back and my Charles Buthod cello came to me via Guivier too. I recommend them highly for honest valuations, a huge selection of instruments/bows to suit all tastes and budgets, friendly staff, genuinely no pressure to purchase, flexible on the time you can keep bows/instruments on approaval, and, for a central London dealer their prices are very good too.
The dealer I (and many of my colleagues) avoid these days is one located in the Ealing area....