There is no thing as Free Delivery as the delivery price is added to the price of the tilesSome appear cheap...but then you add on postage and the bargain ain't a bargain anymore (Victorian; many others).
Postage and packing is expensive as tiles are heavy and generally not insured by courier parcel companies
So if the tiles arrived damaged the sender cannot claim compensation
The companies who offer Tiles at price and then postage on top are selling 2 services
1. For the tiles which they make a profit
2. For the post and packing which they pass the cost to the customer with no profit