First of all, get this book.
http://www.amazon.co.uk/Mary-Bells-Compl...+mary+bell
The dehydrator I have is one of these:
http://www2.westfalia.net/shops/househol...drator.htm
It is probably the most basic dehydrator you can get. It does the job, but it also has limitations. To ensure a quality end product it's necessary to rotate the trays, but then you have to do that with some of the more expensive ones too. As dehydrators go, it's cheap to run being only 250watts. I have had mine 5 years now and it still runs well. I use it on average once or twice a month.
The good points, it's simple, easy to clean as the motor is at the top, cheap to run. It's inexpensive to buy.
The bad points, it needs attention, for really good results you can't just turn it on and leave it.
It has no thermostatic control, which could well go some way to help with quality of end product.
It has limitations on what you can dehydrate, large uneven peices(broccoli and such) don't do well, niether does citrus fruits. However, it makes fantastic fruit leathers.
Would I have a different one ? yes. I would go for one that has a timer and temperature control.
This booklet will give you some idea of what you can do with a dehydrator.
http://www.nesco.com/files/pdf/nah_adj_c...102011.pdf
I also dehydrate some cooked foods to make up my own dehydrated meals to take camping, this includes pasta, rice, cooked beans. I'm a big fan of this chap, he has given me a lot of ideas.
https://www.youtube.com/user/MrBabelfish5?feature=watch
The thing to bear in mind, like any preservation method is cleanliness and time, it takes time to get it right, and to make sure you have a safe product to store.
Oh and yes, you can dehydrate veg!