387 Zloty = 120 USD, not a bad price. Should do nicely, I think. Couldn't see the T/S parameters because the PDF file wasn't there. But hopefully you can tune it low enough for your needs without making the box too big.
As an aside, I was in Warsaw a few times and when I left, I never exchanged my money. So I have some Zloty and Grosz coins. I kind of like having a little collection of interesting coins.