Be a touch careful - these are ONLY fully accurate with the right emissivity value calibration for the material being measured
The cheaper the unit the poorer the measurement might be (I've used £300/£400 units at work). You can buy 'calibration' discs, effectively a matt black sticker to check (or adjust) the values and if you need precise values this may be worthwhile. If you're just after a rough idea then don't worry!
Before you buy ask what the accuracy is

For example the PE1 is ± 2°, e.g. the temperature could be anything from say 25 to 29°C if you're reading 27°C (quite often the accuracy varies over the range and the best is quoted - the best accuracy may be at the top of the range where the emissivity is the highest!!)
Cheers,
Dunc