Robert Downey Jr. could make up to $100 million to return as Iron Man in the next installment of the "Avengers" series, according to a source close to the arrangement. And, as if that's not enough, he could make double that amount again in merchandising and other Marvle-ish deals that are far more complicated than any superhero movie to date. We're told that the "Avengers" sequel's budget will be around $340 million. "Marvel knows that he is their quarterback for these films leading the fans through the adventures," says our insider, claiming that profit-sharing and producer points will help pad Downey's wallet. "To have to find a new Tony Stark and make fans love him would be a near on impossible challenge." Iron Man is worth his weight in gold The 51-year-old Manhattan born, two-time Oscar nominee has so far done three "Iron Man" movies and reprised the role for two "Avengers" films, with the next one, "Avengers: Infinity War - Part 1," scheduled for a May 2018 release. Filming on that action pic is slated to begin in Atlanta in late January, where Downey will lead an all-star cast including Chris Hemsworth, Scarlett Johansson, Mark Ruffalo and Jeremy Renner. Downey already counts himself among the best paid actors in the world, with a worth of $240 million according to CelebrityNetWorth.com. According to Forbes.com, Downey earned $80 million in 2015, which for the third year in a row put him atop their highest-paid actor list. In 2016 — a year that saw Downey do just one film — Dwayne "The Rock" Johnson topped Forbes' list. "His business deal echoes that earning money at the back end has been a key part of his film success in recent years," says our insider, who has close ties to Disney, which is a subsidiary of Marvel and its superhero properties. "Robert deserves what he gets." In 2015, Gwyneth Paltrow, who plays Downey's sidekeick Pepper Pots in the "Iron Man" movies told Vanity Fair magazine, "Look, nobody is worth the money that Robert Downey Jr. is worth." But there's also no record of any actor refusing that kind of paycheck either. Downey's reps didn't return a request for comment.