I think Iggy could have made significantly more on his latest 5 year contract than he did, but I'd also say that was the first time in his career you could say that.
He signed his latest 5 year contract in '08 after a 50 goal, 98 point season. As a UFA he probably could have garnered a long-term, back-diving deal in a large number of different markets. Probably same cap hit, but he would likely have been signed until 2017 or something, and already pocketed about 15M more in the last five years than he did.
Not that he needs the money.