I am having an educated guess - since nobody else has answered. "free depot price" - is probably the price from a 'duty free depot or shop'. ie the price before any local sales tax is added. "ex works price" - I have only heard this used for stone coming out of a quarry. Stone arrives "ex works" or the wagon comes straight from the quarry so you get an ex-works price. So I would re-phrase this as "prices are usually calculated without sales tax or exceptionally at factory gate prices".