Photography by: Getty

HOW IRONIC! Despite amassing a fortune north of $100 million after turning his junkie/jailbird life around, “Iron Man” ROBERT DOWNEY JR.’s not about to become Downey-and-out again – he maintains an iron grip on the family purse strings!

Out promoting his blockbuster flick that’s headed toward a $1.2 billion gross, Downey grabbed a moment to phone wife SUSAN in a near-panic, says an insider.

“Robert told her he’d just realized his cell phone contract was up in a day, and asked if she – or their business manager – could renew it so he wouldn’t have to pay an extra fee if it lapsed. Susan was kinda shocked and said, ‘Don’t you have more important things to worry about right now? We’re talking, like, a hundred bucks!’

But Robert just told her there’s no sense in throwing money away!”