My Wally World had them in stock yesterday. If you have a Academy sports store near you they usally have some also. I have seen them at Ace hardware but are usally a little more expensive. The other way is on line but I'm sure your like me I want it now to ops check the smoker.
Ace hardware carries a good 1 inch diameter screw, dial faced thermometer for 24 dollars. The face is about 3 inches in diameter and is very accurate. It is made by brinkmann and I replaced my original thermo with this type and have had no issues with it ever.