I too am in the market for an internal thermometer. The ThermoWorks RT600C that Gummi linked to (thank you) is currently available for $15. I like that price much better than $73, which is what ThermoWorks currently wants for its Classic Super Fast Thermapen.
Now I do understand that the Thermapen's results are delivered 1-2 seconds faster than the RT600C, and that the longer you leave the grill lid up for temperature taking etc, the more heat you will lose. But I'm curious -- for my basic backyard purposes, how much difference will 1-2 seconds make? In other words, why shouldn't I get the RT600C now for $15, and get the Thermapen later when I've finished spending money on my SS refurb project?