They already signed Duncan to a contract for next year with an option after that. I think next season is the last one for he and TLR in St. Louis.
Lohse was smart to re-sign for slightly less money because I think he knew Duncan was a huge difference maker for him. Perhaps he took notice of what happened to Jeff Weaver when he left after 2006.
The Cards won't go after CC because they have most of their rotation already set (like you said) but mostly because it goes against their philosophy on signing pitchers. They're very reluctant to sign guys to five-year deals like Sabathia wants. As for the hometown discounts, almost all of those were made after the player had already been playing in St. Louis (McGwire, Rolen, even Pujols).
I disagree with the notion that Jocketty wasn't willing to spend money. He did sign Rolen, Izzy, Renteria, Edmonds, Pujols, etc. to long-term deals. I think that really was a decision by ownership in his final couple years here, and it turned out to be good because the free agent market the last few years has been completely out of whack with average players signing above-average deals. And outside of Pujols and Molina, the Cardinals have had virtually no major contributions from players within their own system this decade when Jocketty was GM. Until the last couple seasons, they had traded most of their prospects away for major-league ready talent.