Who was the most productive NFL player you can think of that was originally picked up for dirt cheap?

Who was the most productive NFL player you can think of that was originally picked up for dirt cheap?

And I'm not limiting this to recent players and trades. This can be in any point in history if you feel like. This can be whether it was a drafting, trade, or free agency signing.

Like what player was WAYYYY more valuable than what they were paid?