Work / how much is the salary of purchasing manager in Poland? [7]

Hi, folks
I'm a Chinses. Rencetly a Polish company want me to work for him, my job is to find products and export it to Europe (position is like purchasing manager in Ploand). And they asked me about my salary exexpectation, how much should I say is right?

By the way, I have three years experience in this area, and know English.

Thanks