If you are specifically looking for the Mk4 rather than the newer model, you have a few specialized options:
: The ONE features a brighter, white backlight compared to the Mk4. Tips for Buyers thermapen mk4 where to buy
: You can find used or "open box" Mk4 units on eBay and Amazon Resale. Note that these may not include the original manufacturer's warranty. If you are specifically looking for the Mk4
: Some niche retailers like Smokin' Deal BBQ or Smokin Brothers may still have lingering stock, though many list the item as out of stock. thermapen mk4 where to buy