I have recently had a timeshare based in Manhattan valued for IHT purposes by Confused About Timeshare.
http://confusedabouttimeshare.co.uk/?gclid=COrEpbrcntACFcm6GwodI1AHTQ
They are company, based in the UK, which buys and sells timeshares, and they are members of the Resort Development Organisation, following its code of conduct. They will value timeshares, based on the data they hold about the market, for a fee and will provide a brief valuation report.
Kirsty McGeough
Turcan Connell