Not strictly speaking true. Unlike CD and DVD where a bog standard package would be no more than 20p, with each console game that's produced the format holder is paid a licensing fee straight away (rather than say royalties to an artist which are paid only when sold) and as such production costs are higher. This was true as of 5 years ago when I left the industry, I assume it still is.
@jablonski maybe not a couple of pence but the physical disc isn't worth much . That being said obviously there would be a mark up on the product to cover the retail costs and profit tsrgets.