My question is very simple, I have an idea, I constructed the machine, it works. Now, the question is does it worth patenting it? I mean, the amount of money in order to patent is not little for me where I live (EU country). Moreover every year (for the next 20 years) I should pay an amount of money that increases in every year..! So, how can I find out if the market is going to buy the machine (the patent) I thought of??
It is actually a very hard question. It is also probably off topic as it is really a business question rather than a patent question. Regardless, I'll give you a few thoughts.
First, your machine may or may not be patentable. Just because you don't see it in the market doesn't mean someone hasn't already patented it. It might not even be considered sufficiently inventive. You should try searching for similar technologies on Google Patents or The Lens. This takes some work and there are answers on this site related to doing patent searching.
I have worked for startup companies. Valuation is maybe the biggest question. You have to predict sales, manufacturing and sales expenses, etc. to figure this out and there is no way we can help with this. A lot of inventors team up with business people with startup experience. You don't need a patent to do this, but you should have a non-disclosure agreement with whoever you show your machine to. If you get investors then you can use that money to pursue a patent.
value is in the eye of the buyer, no one can give an answer which is either yes it is worth patent or no it is not worth patent. worth is not only dependent on the idea alone, it also depends on what you do with the idea (patent it and make a business out of it, license it or wait for someone to approach you with funding), how the market receives your idea etc.
This is more of a business question than patent related so you take a decision.