To add to the above; the vast majority of socket testers detect the same range of faults. Some have an additional RCD trip function, but I'm not sure that's a feature any of us need. No matter the price, I'm fairly certain that none can detect earth/neutral reverse and for that reason I consider their main use to be making enough noise so I can hear which breaker seems to isolate a particular circuit and this isn't a function on which vast sums needs to be spent.
It's unlikely that I'd ever buy an unbranded tester, but nor would I spend more than the bare minimum.