I've got two. One is an RAC one and the other I can't remember the make but I got it from Halfords. The two differ by a couple of PSI and I think the Halfords one is more accurate than the RAC. IIRC the RAC one came as part of a kit from Lidl which included a tread depth gauge and a couple of other bits and bobs. Neither cost more than £10
I ended up with a bluepoint analog gauge, which appeared to be the way to go without spending silly money. All depends how acurate and or repeatable you actually need.