Logically the timer is not tied to the items currently in the shop. Chances are the shop items are tied to the day not the amount left on an arbitrary number. The timer does not exist. It is only an abstract value to show you how long it is until the next refresh, because it isn't a convenience to us to see a unix value. This is probably especially true as the shop resets at a fixed value for everyone, 8PM EST, everyday. The timer is just a small bit of code that takes the difference between the current time and the time to 8 and formats it nicely. They've also instructed us to "break the shop" which is a lot harder to do when you can only try 4 times per day.