deux jambes

Minimal funding = elbow grease, Turtle Wax rust remover and chrome polish and scotch brite.

Slather it on the bad spots and let it soak in, sit, slather again and scrub with the pads, also slathered, repeat as necessary, may be several times. if the first tries are weak let it sit and soak longer, even overnite.

Depending on how bad, this will remove most/a lot of the rust so you can see, if it takes it all off you can prime or touch up those spots for now while you figure out what to do with the really bad. It will usually get it down to where it can be sanded out the rest of the way.

A drill with a wire wheel would also be a great help if you have or can borrow one.

Evaporust also makes a gel that works ok but is spendy, regular liquid with rag wrap in a garbage bag should work pretty good once you get the top layers off with the remover and elbow grease.