I think its an urban myth these days that everything on the continent is cheaper. 
I was in Hungary in the summer and I was shocked at the cost of things. A basket of beers and snacks from Lidl was more expensive than I would pay at home! 
It's Eastern Europe FFS. It's supposed to be cheap!

As a rule of thumb, always pay in the local currency if given the choice as you use your card. That way you pay the official conversion rate as the transaction hits your account rather than whatever imaginary rate the retailers cars service provider chooses.
I paid cash in Hungarian Florints. I sat in the car, looked at the receipt, thought
Fook me that seems expensive. Then did the conversion to Sterling, and thought
Fook me that is expensive! 
Two things about Hungarian Lidl.
1) Every one I went into was absolutely rammed. So I guess it's the cheapest supermarket in Hungary.
2) When you pay at the self service tills, you are confronted with a barrier on your way out. To open it, you have to scan your receipt. It's a good idea, but it flummoxed me momentarily!
