I just got one recently for about $25 at Wal Mart.  It does have a fan, but
no thermostat, and 4 shelves.  They had a couple of other models on sale,
up to about $40.

So far I've tried apples and pears a couple of times. The pears always seem
to come out tough, whereas the apples are a bit lighter, almost crispy.  I
think I'll stick to the apples for a while, since one of my goals was to
get something crunchy to substitue for chips, crackers, and other
"forbidden" snacks.

Here's a tip I figured out:  the instructions say that for many types of
fruit, you should pre-dip them in some form of ascorbic acid to prevent
them turning brown.  I found an ascorbic powder at the supermarket, near
the canning supplies, but reading the label showed that it was mostly sugar
:^( .

But the instructions say that you can use fruit juice, since it has vitmain
C in it (which is the same as ascorbic acid, right?).  Rather than use my
good drinking juice, I tried taking some of my vitmain C capsules, and
dumping their contents (pure crystallized vitamin C, according to the
label) into a pan of water -- about 3 caps into a quart of water.  I slice
a fruit, put the pieces in this solution while I slice the next one, and
then move them on to the dryer shelf.  Seems to work fine.

Have fun!