depending on how many you are drying and how big your harvest/flushes are, a commercial grade dehydrator with multiple shelves is great.  very very low heat (myths about heat and mushrooms abound - they actually withstand heat pretty well before degradation....ever make tea with boiling water?  doesn't hurt a thing!)

after they come out of the dehydrator, let them sit in open air for 24hrs or so - any last bit of moisture is easily evaporated then.

invest in a vacuum sealer as well - that's where desiccant is useful.  put one of the small sacs of desiccant in the vacuum seal bag.  they'll last for years if kept cool and dark.