Rust and the Solution

[Sidewinder]

Hey Guys,

For many months now, I've had this problem. It's getting worse. Here in Wisconsin, its nearly inevitable, but it's rust.

On both the left and right doors, in the groove created by the door sheet metal fold and the body cladding, there is rust growing. It is growing down the crack from the front to the rear.

What, if any, solutions are there? Worst case senario: new doors. If that's the case, what do a new (used) set of doors go for?