Garden Patio Slabs, Price?

So I was just wondering if anyone new the average price for a patio slab? All I can find is sites with no prices. Basically I want to know how much the slabs cost because we already have someone who'll lay them free of charge. no fancy slabs either just the basic grey ones. thanks in advance to any helpful answers :) oh and I'd like to know the price in euro if possible :)