yeah if you're going to spend money on something that don't work you might as well spend as little as possible and do it yourself.
Voltage is important but if the output is low wattage then when the load is low resistance the voltage won't go as high as it normally does. (Watts=voltage x current)
DC offset, duty cycle, frequency, don't matter because "Rife" machines aren't Rife at all. His technology was for sale and his secrets died with him because he never found a buyer. Modern Rife technology is nothing more than a fad. I used to sell them but stopped because my customers weren't getting good results. Beck technology is something that works and is relatively cheap.