Admittedly most of mine are cheap ones. But they all read about the same. I set the dehumidifier to the lowest relative humidity possible and it is plugged into a receptacle that is controlled by a Honeywell humidistat. The setting on that control and the hydrometer stay within 2%-- I consider that to be very acceptable.
You could buy a number of cheap ones and one that you trust more. Placing them near each other for few days will show the accuracy- or not- of the cheap ones.

A small Sling psychrometer is not that expensive.