The Thermapen is currently available from the manufacturer for $74: ThermoWorks - Home of the Original Super-Fast Thermapen!
And despite the conservative claim that it reads in 4 seconds, it actually reads in about 2 seconds (I just checked it with my coffee). And yes, that speed is very important to me, especially when I have my arm stuck in the oven or over a hot BBQ grill.
The Thermapen is accurate to within 1%, which isn't all that important in cooking but it's comforting to know that, unlike other instant-read thermometers if used, it's right.
It's NSF certified and meets the USDA requirements for accuracy.
The probe needs to be inserted only about ½ an inch for an accurate read.
And the ½-inch tall numbers in the digital readout are large enough to read at arm's length, important when you're checking something in the oven or on a hot grill.
Lastly, it has a range of -58 to +572 degrees, making it more versatile than most others.
So, yes, for the same reasons that Cook's Illustrated gave the Thermapen three stars (highest rating) in accuracy, speed, and functionality and gave it the only "highly recommended" rating in its June 2008 review, it's worth the extra bucks to me.
Of course, I think nothing of spending $200+ on a kitchen knife, so don't listen to me.