How should I address my lower quarter rust on a budget?

if you dont have a welder you can use jb weld or maybe even window caulk, and hold the patch in place with sheet metal screws until it has cured. take the screws out and slap on a little bondo. everything you need can be bought at lowes except for the bondo. or you can go to walmart and get a fiberglass repair kit and patch it that way.