I built a UDS a couple of months ago and I used a turkey deep fryer thermometer, which is 12" long. Originally $15 at Academy, I got it on sale for $3 or $4. You can calibrate it, which I did with boiling water, and it holds true with my digital probe thermometer.

I broke it in with a couple of fatties, which seasoned the drums nicely. In the last 2 months, I've done several whole chickens, St Louis ribs, and a Boston butt for pulled pork. I've always been a fan of ribs, but after the pulled pork sandwiches with homemade Carolina sauce, I think I have a new favorite smoked food. Pulled pork sandwiches were always ok in bbq joints, but damn, homemade is where it's at.

This drum beats the living hell out of my old offset. Inexpensive, huge, effective, and fun to build.

 

I have built 2 UDS and have turned out a ton of great food over the years.

I always look on craigslist to see if I can score a green egg or Traeger for a song but its hard to beat the UDS for the price.

I think I have $75 into my first one and about $10 into the second one I built.