This is the lowest price I can recall on brand new Thermapens. They periodically do an open box sale on refurbished models. That's typically $2 less. But as far as brand new, Thermapens, this is the lowest I've seen. The email I received said that quantities are very limited.
The Mix and Match sale allows you to get the volume discount (usually need to purchase 5 of the same item) by purchasing just two items. It's worth noting that you can pick two different items to get the discount.