Three products I can recommend.
Pro's Non-Acid Wheel Cleaner is great and it is pretty cheap. You'll have to email them for your local distributor but sells a gallon for $11.50 and they also sell 5 gallon jugs for $45.00 (Only $9 a gallon there!)
Pro's Green Nitro also works on light brake dust (As long as you do it every couple weeks before the wheel becomes solid black this will take care of it). You have to spray it on, let it sit a few seconds, and then use your wheel brush to losen the brake dust and wash it off. It also works great for cleaning Tires and Wheel Wells. It is $9.95 a gallon and $39.95 for 5 gallons!
Autoint's Omni All Purpose Cleaner is also good. One gallon of it is $17 but it is concentrated at a 10:1 ration so you get a LOT for your money. I haven't tested it out enough but it seems to work well on brake dust. My wheels weren't black when I did it but they didn't have light brake dust either. I'll test it tomorrow again on another vehicle. You have to spray the wheel down and let it dwell for about 30 seconds to a minute, then scrub, and rinse off.
The Autoint stuff is also suppose to be okay to use on paint for bugs, bird poop, convertible tops, interiors, etc. It works on dwell time and isn't suppose to contain anything that can damage parts on your car.
PRO stuff you can check out at prowax.com and email to find a local distributor.
Autoint stuff you can check out autoint.com They prodcuts are called Valugard.