I'm in Poland and looking to save a few bob in withdrawing my money.
Is there any guidance as to which banks cost the most for withdraw?
More generally. Is there any such source by country? That would be great for future travels.
I'd say it's quite complicated and dynamically changing. Until recently, in most banks, ATM withdrawals were free. Currently, due to law changes, more and more banks introduce charges for ATM usage or increase fees for it. It depends on couple of factors - it's different for private accounts, different for companies. Most banks charge for giving you the card at all (couple of zlotys per month), but you can avoid it if you use the card for payments (for example - you won't be charged for having a card if you do card transactions for at least 300 or 500 zl cumulated over the whole month)
I am not aware of any list with such information where you could see all the banks compared