The only way I can keep my chrome rims clean is by cleaning them ver often. But usually I don;t have much problem with it because I use the wheel cleaner. It works so well and I think that is pretty much the only way you can make your rims looking new. Cleaning your rims before the brake dust gets too heavy is key. Maybe you can also think about investing in a big brake kit which will eliminate most of your unwanted brake dust. If you do find a good deal on a big brake kit, please tell me too. The cheapest Brembo package I can find on my 01 sc281 is about $1100... and only for the front ones too!! And they can go up to about $3,000.
The company that makes POR-15 epoxy paint for your chassis also has a marine grade clear coat called "pelucid" I think (?). I'm not sure how good this is, but they say you can clear coat anything and it holds up.
Other than that, a good coat of wax and regular cleaning will do the trick. Don't use rubbing compound when you buff these out. Over time that will dull the rims.
Call the company who makes/sold you the wheels and ask if there is a reputable company they can refer to you so that you can have the wheels cleared.
$80/wheel may seem a lot, but it isn't. Look at it as an investment for the long haul. If you run these wheels in the winter, you better clean them and wax them everytime your car gets hit with salt.
My Cobra R's are chrome and the chrome is flaking off in huge chunks just after two years of use. This is due to winter use. Had I known to have them cleared, I would have done it. Now my next set of wheels will only come on after winter and be used for only about 5 months out of the year.
I learned my lesson the hard way and I would hate to see you do the same. Invest the money.