Used Rife machines are always for sale. Why? Because they don't work!
I used to make and sell Rife machines but stopped due to my conscience bothering me. Other than a few exceptions, such as 464Hz for candida, they don't work.
Rife machine sellers teach how the inventor Royal Rife used his machine successfully against cancer and different microbes. Then they let you assume that their "Rife machine" is the same that Royal Rife used although the original design and frequency list died with Rife since he kept them secret in hopes of finding a buyer for his technology. Also the common "Rife frequency lists" are allowed to be assumed to be from Royal Rife which is not true. In 2009 Don Tunney, manufacturer of the PERL Rife machine, died of cancer due to radiation exposure. If Rife machines cured cancer then of course he would still be enjoying life.