I think you will find all of the above (all cheap digital thermometers and IR guns, all IR guns are about the same +/-2ºF) . Just plan for the deviation it is very hard to find accurate on a budget.

I have not checked rancos but Johnsons are the same too. I'd be surprised if rancos were different they simply do not need to be for the intended purpose. Herpstat, Helix, VEs and Ecozone all are about +/-1ºF just keep in mind that the temps can be higher or lower than you expect and plan that when you set the temperature. I'd say 92 is a touch high, personally I'd go no higher than 91º