Consumer alert:
For those apprehensive about ordering a product with a less than perfect reputation for reliability from a Hong Kong company such as Humminguru (understandable imo), that ultrasonic cleaner is now available on Amazon. $499 (free shipping, of course) for the machine and the optional adapters for 7" and 10" discs.
I don't know what the warranty is like, but if you buy on Amazon you can at least immediately return the HG hassle-free if it arrives DOA. If I had $500 to spend on a single cleaning method, I believe I'd go for the HG.