Most produce can easily be dehydrated with little preparation. I do even less preparation than is often recommended because I'm kind of lazy (okay maybe it's more about being busy but still). Some foods brown when they come in contact with the air and it is recommended that you soak them in lemon juice to prevent the color change. This creates a prettier end product with a slight lemon tinge. I don't like the lemon tinge. If I eat a dried banana, I want to just taste banana. So my fruit doesn't always look pretty. It's not pretty when I mash it up between my teeth either so what do I care.
You don't have to buy a dehydrator to dehydrate foods. I like the convienence of a dehydrator but I've also had mine for nearly 15 years. They do get pricey but mine was a bottom of the line, not fancy sort of machine that has given me nothing but pleasure. The only disadvantage to my dehydrator is that it is round with a hole in the center for air circulation. For most things, the shape doesn't cause a problem but won't work for long strips of vegetable or meat.
My mother found her monster of a dehydrator at a garage sale. It has long metal screens that remind me of window screens for drying the food (compared to my plastic grids). The advatages she has is there is no problem getting her harvest on the screens, the openings are really small so no falling berries (my elderberries did a lot of escaping) but the sheer size of the dehydrator is a pain.
I share these things because it will make a difference when you go to purchase your own. It's not enough to look at the features of a product but how and where you will store and use it makes a difference we don't often think of.
As I said, you don't have to have a dehydrator. You can dry in the oven or in the sun. Alton Brown has an awesome way to make jerky using a box fan and several paper filters (the sort you use in a furnace). It's my plan to try his method someday. I believe paper filters are rather inexpensive at Walmart.
I have seen many books on drying foods. These are great for learning, especially if you are not using a dehydrator. My dehydrator has settings for each type of food and I run it until the food is really dry. If there is any concern, I throw the food in a freezer bag and freeze it. It may seem counter-productive but freezing dried fruit takes up a lot less space than the whole fruit.
WSU has a good beginner site and your local library should have plenty of books. For creative dehydrating recipes, check out raw food books and sites. One site that was recommended to me was Gone Raw.