humidity checker for plastic pellets?

I know there's a "moisture meter" for checking moisture content in wood.
Can it or some other tool be used for checking the level of humidity in my pellets before feeding my Filastruder?

I would think it would work but the absorption rate for plastics is pretty well documented so you can more easily work out what the moisture content will be knowing how long it has been open for. You could also weigh it to get a pretty accurate estimate.

I know that I am reaction to an old thread, but since I have the same question..
I'm researching ways to dry plastic pallets before using them in my filament extruder and I am looking for a (not to expensive) moisture testing device. Does anyone know of such a thing?
The only devices that I find are are more than 500 dollar.