Meghan Markle and Price Harry could be “sitting on a gold mine”, an expert has said The couple, who moved to the US after their split from the Royal Family, have engaged in several deals, endorsements and property moves to keep up their finances. Harry’s memoir, Spare, became an international best-seller with more than six million copies sold and earned the prince a reported $20million advance for the book. However, royal expert Tom Bower suggested that Meghan’s autobiography could also bring in a lot of money for the couple. The author of Revenge: Meghan, Harry and the war between the Windsor…