rust protection

Hello, new member here. Just bought my second buick century in my lifetime. 2003 from Florida, with 77k miles and not rust...would like to keep it that way. Does anyone have any sites to get rocker panel covers? For under the doors. I know with having a century before that theses love to rot...

Just wondering if those living in the snowy areas got rust proofing and paint protection for their cars. I backed out of it as it was about 900 bucks for both. The dealer here at MN tried really hard to push it but I denied it at that time. My Jeep Grand Cherokee has a little rust at few...