any hardware or DIY shop should have Brasso....I've tried using polish/wax/Brasso..to be fair each of these have its own advantages but depending on the type of paint on your rims.
Basically white rims are the hardest the maintain because of the brake carbons..but one thing for sure...avoid using anything that is rough to rub/clean ur rims as it will erase the gloss on the rims....you should try something liquid i.e. the liquid zip...also avoid using axion