Before you start going crazy buying things try out some different methods on your least valuable chips. Ultrasonic is definitely effective but you have to ask yourself what you have, what you anticipate getting, and what your usage is. If you don't already have an ultrasonic cleaner or the ability to get your hands on one it's an expensive proposition for something you might rarely use. Unless you're running a casino it may not be for you other than the first clean the whole collection exercise. The disclaimers at the start of the Ultrasonic Chip Cleaning thread are well heeded.
You really want to clean your chips as infrequently as possible. As others noted you're going to get some color loss each time, plus potential damage to inlays, hotstamps, etc. Assuming you play twice a month if you're cleaning a given chip more than once a year it's time to start handing out paper towels to your group after pizza breaks. Actually, wait ... you should be doing that anyway!
One thing I've found to be highly effective after scavenging chips from a new casino is to hit up the hotel gym. They usually have a jar of industrial sanitizing wipes with a chemical name 39 characters long. A little bit of rubbing around the edges with that and 15 seconds with an "oops I forgot my toothbrush" from the front desk to get the crevices and those babies will shine in no time flat with no visible damage. Magic Eraser is good too but keep in mind that it does contain a mild abrasive.