As one of its daily deals, THAT Daily Deal offers the Mathletes T-Shirt in Dark Blue for $4.99 plus $2.99 for shipping. That's tied with our October mention and the lowest total price we could find for this shirt by $11. It's available in sizes S through XL. Deal ends December 25.
Note that size XXL is available for an extra 99 cents, and size 3XL for an additional $1.99.