value of secondhand roof tiles

[Elensw]

The builder who is quoting for our renovation work says he has contacts who will buy the tiles from our old roof - they are the little slate ones, oblong shaped with a point at the top. i understand are very expensive new / difficult to get these days as they have to be handmade. Has anyone bought any roof tiles secondhand...what is the normal price per tile as i want to get the best price possible!!! Essential due to cost of new roof!

Thanks.