Torque specs on a MX5 aren’t exact;y like, say, an aircraft, where tolerances are much less. Everything has a range.
NA/NB torque specs
https://www.miata.net/garage/torque.html
Wheel nuts; 89-117NM. so 103NM is bang in the middle, a 13.6% variance. For wheel changing, 13.6% accuracy is good enough, if you always (as you should) select the middle rating. But propshaft bolts are +/- 5%, sparkplugs are a whopping +/- 21%. Sometime, I need to convert those specs into tolerances, but not now, as I’m sitting on a beach in a faraway place. But 5-20% tolerance doesn’t suggest high precision tools are needed for the typical home mechanic. I come from an industry where we think in terms of +/-0.01%.
The one exception is cam cover bolts, which is why people ask about low end torque wrences. These bolts are seeminglyh made of chocolate, so I look at the low end setting. I’d look through that list of settings, decide which jobs you are going to do, and let that determine which tool you need to buy. If you are going to do complete engine and gearbox rebuilds, then you probably need to spend the dinerae on a Snap-On or similar.
For what its worth,my general purpose torque wrench is Blackspur, and for the once in 5 years job, a Kamasa. Do I recomment Blackspur especially? No particularly, it seems neither good nor bad, because I have nothing to compare it against, in terms of experience.
In the shop, open the torque wrench case, and look for the calibration sheet, where some engineer, in the factory, would have run some checks and signed it off. Even the cheap Chinese ones will have this. If there isn’t one, the tool is a toy, don’t bother with it.
Most torque wrenches on sale through tool shops, like Machine Mart (Clarke’s in Machine Mart’s own brand), will be good enough. More importantly is consistancy; is the design of the wrench such that it is easy to set it, and the setting doesn’t drift during use (usually you adjust on the handle, but the scale is sometimes not easy to see, and you set with a locking nut, some of which don’t lock that well).
Don’t bother with Aldi for tools. They are not that cheap for the price you pay. ie. cheap stuff is junk.