I had to make some compromises to get the differential thermometer I wanted.
My priorities were:

1. Size
2. Country of origin
3. Ease of use
4. Accuracy
5. cost

Final decision is the UEI DTM 304. Four K-type inputs.
NIST Calibration Certificate.
Self explanatory operation.
Fits easily in one hand.
Temp off set, back light, big screen and numeral.
Made in Korea.
Less than $175 shipped.