I have two from Sealey. One does 5-25Nm (the STW101) and the other does about 20-70Nm. They cost about £25 inc postage when I bought them. If you shop around, the price probably hasn't changed that much. I bought a set hex keys to fit the wrenches on
Ebay for about a fiver. They both come with calibration certificates.
There may be better or cheaper ones around but, at the time, they were good value.