EXCLUSIVE Meghan Markle<strong style="box-sizing: border-box;"></strong> and Prince Harry<strong style="box-sizing: border-box;"></strong> should have no problem becoming self-sufficient ... because there are huge sums to be made for speaking engagements and book deals. The Duke and Duchess of Sussex would easily command upwards of $500,000 each to speak in front of crowds ... according to folks who help celebs get such deals. Lots of famous folks get paid huge sums to speak, and Meghan and Harry are obviously in demand. GDA Speakers, whose clients include Nicole Kidman and Diane Keaton, predicts baby Archie's parents could do a lot of business speaking in front of non-profit and volunteer-based organizations, and they'd get more than the standard $200,000 to $300,000 going to most celebs. Meghan and Harry could make even more by putting their names on a book ... celebrity and sports agent <strong style="box-sizing: border-box;"> Darren Prince</strong>  tells TMZ, the former Royals could easily bank an $8M to $10M advance on a book deal. The final amount could be even higher because we're told the $8-10 mil figure would…
