Hi @narciso, for now the most "cheap" is that, that of Abbott's freestyle, since Dexcom depends on what the sensors last, and you have to make a bigger initial investment.
With the freestyle the initial pack will cost you € 60 the meter and 60 each sensor.With an initial investment of 180 euros you have a month to test the system.If you do not convince you, the 60 euros of the meter are not going to recover them.
As a personal opinion I think that if you use the information you give you you will learn much more in a month than you have learned in a year.It is a good investment that has changed my life.If it does not work for you, you will have "thrown" 180 euros, I think it is worth trying with 9 ...