Not sure of your point, but regardless of where you buy it, you need to check it. If it's stuck in the side of the smoker and it's been banged around, no telling what it reads.
It's usually pretty easy to check them. Make a pot of boiling water, and depending on your altitude, you'll be able to see if it's close or not.
For a remote thermometer, just go to a local store (walmart, target) and look for one. Get it home and test it also.
Hope that helps.