Ironically, there was a thread on here a few days ago entitiled "What is the worst Household Item you have ever bought?"... the food dehydrator, as it's named here in the U.S., would certainly rank at the top of my list.
Firstly, one has to be truly dedicated to the art of food storage to make sufficient use of the device to warrant the fairly expensive acquisition of one. Here in the U.S., they start at over $100 and can run to nearly $500. They take up a lot of room if storage is a problem and they take a lot of time to dry the foods so counter space is important for use of the machine.
I would suggest that you try dehydration of a few items (there are on-line recipes) in your kitchen oven. In fact, some, at least here, have a setting for "Dehydrator". It would give you a good flavor (pun partly intended) of whether the result is worth the cost and effort...