jaycar has some , think its bout 24 bucks
stinger has some
second skin is another one
steer clear of bunnings for that stuff
spray foam works in certain spots but can corrode metal, rot out, trap water fron getting out of the car, BEND/Buckle panels
concrete but not good unless your towing the car to SPL comps.lol
spray sound deadener from the autoparts paint supply, comes in a brush can as well, or truck bedliner works,,,, but they must dry and be able to be touched, or the mess is huge. the tar ends up everwhere
some normal type foam core work but expensive to get
duck tape can seal doors crudely, but you need decent brand tape, in black to look ok and spray glue to make it stay on properly