"Since it is not possibile to search for repeating fields and show the post but only the repeating fields"
I don't understand what that means.
Do I undertand what you are trying to do correctly?
You have a custom field for minimum price and a custom field for maximum price. You want to filter by both of these fields, but you only want one filter control—for their maximum budget—and both query filters should take their value from this one filter control. Yes?
The problem looks like you are adding a filter control for a field "wpcf-costo-a-persona":
[wpv-control-postmeta display_values="Costo Massimo,10€,15€,20€,25€,30€,35€,40€,50€" values=",10,15,20,25,30,35,40,50" field="wpcf-costo-a-persona" type="select" source="custom" url_param="wpv-wpcf-costo-a-persona"]
But wpcf-costo-a-persona is not the field you are filtering by, and it is being included in the SQL query.
I suggest you delete your existing filter controls and query filters and start again.
Then insert a filter control for one of the fields you do want to filter by, say, the minimum price.
This will use a particular URL parameter. You can change the URL parameter added with the filter control to something more generic, e.g. wpv-costo, and edit the existing Query Filter for the minimum price so that it takes its value from that URL parameter.
Then insert a second Query Filter, this time for the maximum price, and set it to use the same URL parameter (and the required condition, e.g. less than or equal to).