Hi Pepito and welcome to the Forum!
First let me say that your plan to give coverage over Spain sounds wonderful - really looking forward to seeing it live on the network!
In answer to your question, yes, all the network users are indeed contributing to the network, as well as receiving the data.
But remember what AirNav are doing. First, they are providing the servers, and, despite a few little problems in the last few days, it's a pretty good service. Then, they are adding a lot of value to the data by providing the aircraft data lookup, the routes lookup, the photos lookup, and their excellent support and continuing enhancements.
I personally think that 5 Euros per month is very good value for all that. You are not alone in questioning the cost, but to me, 60 Euros per year seems to be well worth it.
Rod