"The idea of "free" valves for testing would be like, I don't know, high end matress sales, try it for 3 months, if you do not like it, send it back, no charge. If you like it, in three months, you pay for it."
I kind of like that idea... If it does'nt work for you send it back... If it does (Which many of us that own a DynoValve, know that it does...) Pay for the DynoValve with the some of the money it has saved you in the past three months.