Caramel gliders are a subspecies of our sugar gliders, and they are not "rare". There are a few breeders who specifically breed caramels and 350 a pair is is about average for price for a pet only. I've seen singles go for 300 with lineage just depends on the breeder and what their location is. Prices for caramels are usually a little cheaper than regular glider prices which is strange because many people seek them out for their calmer disposition.
Location often times has to do with prices on gliders, as much as the color and lineage of the gliders because depending on if you ship, utilize the internet or have 6 other breeders in your area all affects your selling market. If the breeder has no other breeders around them they can charge higher prices than a breeder who has 6 other breeders they are competing with.
Caramel glider characteristics
They are larger in size than our regular gliders
the are said to have a thinner stripe down their back
thicker nails
slightly larger ears
rounder face
much thicker tails
and fluffy white fur on their hands
their coloring is not a "brownish or caramel" color it's more of a silver grey or champagne grey.
They are also said to be mellower gliders.
There is a member here that only has caramels her name is RustyPossumFart you can look through her pics to see what hers look like
http://www.thepetglider.com/gliders-for-sale/category/59-caramels.html
There is also a group on facebook specifically for caramel owners with lots of pics
https://www.facebook.com/groups/1590606094490532/