Just to give you some indication a painting by him was sold for 14 million dollars in May 2005 http://money.cnn.com/2005/05/11/news/new… Why don't you get a valuation. The big auction houses Christies/Sothebys etc. usually do this for free in the hope that when you come to sell you will do it with them. The first stage is to phone in and they will tell you to send in a photo and other details.