For products which have variations either a choice of say finish, length or even quantity you will need to select the options you would like before the cost of the item is displayed.
In many ways this is an improvement on the system we used to use. e.g. customers previously would need to add to cart before being shown a price for a combination and also perhaps more of a priority it is clearer in explaining how many of certain products were being purchased. Previously customer would by 1 of something expecting a pk of say 10, and more often than not we sell items indiviually as we buy them in bulk.