Door and truck stripping

OK so for the last few weeks I have been drying the floor boards both drive and passenger because when it rains my floor boards fill with water.What I think is the water is running down the rain guards on the windows and right in the door jam.I have also getting water in the trunk.I know the stripping there is dry rotted.Were can I get some door jam and truck weather stripping cheap like 35 dollars for all cheap.