Hello,
I'm native Polish speaker, and I can provide you with translation in that language. Error free, because I indeed working with good proofreader. My previous employers was very pleased with my work, what you can check on my profile. Deadlines shouldn't be a problem, I'm working pretty fast.
Normally, my rate per word is 0.05$ (including proofreader payment).
But, because this would be my first work for you, price point is lower. That way, you can judge for yourself if my services is what you are looking for.
Regards,
Dominik