Trade organisations generally have data on the market. It is generally one of their objectives: improving knowledge and the transparency of production and the market of a sector, including by publication of aggregated statistical data on production costs, prices, etc.
There is no need to ask any national authority to certify these data. In an application for EU funding, these data shall be easy accessible (extract of studies or link with webpages, etc.).
In addition, there is a second possibility to demonstrate your representativeness. Lower thresholds may be accepted in duly justified cases, such as the structure of the market.