Income from the Duchy of Cornwall is approx. 25 mil USD. From the Duchy of Lancaster it is about the same. The sovereign grant is approx. 55 mil USD. Then whatever their personal investments yield. They are not permitted to sell assets from either of the Duchies either so I have no idea where this rumor of them selling land off comes from. PC has actually expanded his land ownings for Highgrove and neither Balmoral nor Sandringham have sold any land from those estates.