I have paid for 2 (and more than once!) just for comparison. It is worth it to me to be able to choose my favorite shade. In most cases, it’s not that the sales associate is playing games, it’s that the item will be sold very quickly to a customer, so it needs to be paid for in order to reserve it for comparison purposes. For items that are in lower demand, or if the store happens to have multiples, they are happy to let me choose from what they have on hand without prepaying. It may be unfortunate, but it is normal.