I bought a Halfords "Deluxe Tyre Pressure Gauge" a couple of years ago, seems quite accurate (+/- 0.5 PSI), can't recall the price but it was not a lot.
I bought the Ring RAC 600 because it goes up to 100psi - my van tyre pressures are 65psi and I found many gauges only go to 50psi. 3 friends have also purchased the Ring - an excellent piece of kit which I can recommend.
I purchased a Halford digital gauge because, like other, my previous gauge did not go above 50psi. I also have the Ring compressor in Bowler post above and its a good bit of kit and saves a lot of foot pumping!
I use a RACE X PROFESSIONAL pressure gauge. It has a clear dial (analogue) and has a max. reading of 60psi. Ideal if you don't need higher pressures.
I always raise and lower my tyre pressures, depending on solo or towing. My existing 12-volt tyre inflator was getting a bit rattly, so I have bought a Ring heavy duty 12-volt inflator. It has to be used with crocodile clips direct on the battery, because it is 23 amps. But it is quick, and quiet. It cost £60 but well worth it.
If you use the 4psi rule (lots of references on Google), your tyre pressure gauge doesn't need to be accurate, it just needs to read consistently - which most gauges do.
I have had used a 'Draper' tyre gauge for the past 6 years and is really useful because you can lock the dial pressure then read it accurately which is ideal for when bending down to check the tyre pressures. I was also informed by a tyre fitter that these are used by professionals to due their accuracy and reliability.
A bit of topic but,someone told me that a fore court pump will not blow up any higher than 50psi,which got me thinking.There must be a lot of light trucks out there with under inflated tyres..