An original Claude Monet is worth so much that appraisal costs are immaterial.
Here is a painting that has been in private hands since 1936 and sold for over 18 million pounds.(That converts to $27,620,000 on today's exchange rate.)
http://www.independent.co.uk/news/uk/thi…
July 25,2008 London
Monet sells for record eighty million four hundred thousand dollars.http://www.nytimes.com/2008/06/25/arts/d…
In 2004, London, the Parliament, Effects of Sun in the Fog (Londres, Le Parlement, trouée de soleil dans le brouillard) (1904), sold for U.S. $20.1 million.
Christie's has sent representatives to my house in Ohio to look at, and give an initial evaluation of works worth much, much less than a Monet, packed and shipped them to NY and paid for the final appraisal and authentication. Of course I listed with them. Swan gallery has done the same thing. Any reputable gallery will be tremendously helpful to your friend. If your friend has a Monet galleries will be more than helpful. The art market is soft right now, but the very top works from the super stars demand high prices anytime.