About 1.5 years ago I bought a cheap ultrasonic cleaner. When I am stuck in the house because of illness I look for stuff I don't need to spend money on.
Anyho. After this lenght of time using the thing to clean my chain I have been able to get well over 12,000 miles on my seven and eight speed chains. When I clean the chain in simple gree and water I spend time inspecting and cleaning the rest of the drive train. So the chain spends 24 minutes in the cleaner. When I drain the solution there is a very fine grain dirt in the bottom of the cleaner.
The thing is worth the money considering the longer life of the chains and drive train.