I think that chrome polish and rust remover are going to be kind of different steps and entail different products. I'd also warn you that if the rust is bad enough, there's no polish in the world that will bring back the shine. The shine finish isn't just hiding under the rust, it's literally gone.
So rust removers abound- light rust will come off with something as simple as WD-40 and scotchbrite pad, up to something like naval jelly, which is a phosphoric acid in a jelly base. A lot of the rust removers use some version of this chemistry- acid changes the ionic charge of the iron to break down the iron oxide in the rust, and you're left with a phosphate compound in it's place. CAUTION THOUGH- I make no claims as to the stability of otherwise healthy chrome under this acid treatment. I really don't know what a powerful rust remover will do to chrome. I'm betting for rust removal, elbow grease is more your friend than chemistry.
Once you get it cleaned up, you can move on to the polishing part. I'm not sure that 'good' and 'cheap' go together very often with this kind of stuff, but in general, the Mothers brand line of polishes and stuff are generally respected.
For true chrome polish, this is the stuff I use: Simichrome. It ain't cheap, if I recall. Probably ~10 bucks a tube. maybe more?? don't buy it real often.
