Hmm..I living in Hungary, your location is Poland. I think the hungarian price useless for you.
But okey. The simple matte paint in 20ml bottles cost 80 Eurocent, the metallic and pearlescent paint in 20ml bottles cost 1 Euro. Oh, I use primer paint, this 2 Euro 50 eurocent in 100Ml bottles. I buy these paints in the local "Creative-Hobby shop".