I'm in Colorado, and no one will rehome a joey to me, since I don't want to pair it. I’ve done quite the research though, and single sugar gliders can still be happy. Or can they? If given attention and all other necessities are taken care of... I guess I’m not so sure anymore. Help would be much appreciated!

since gliders are colony animals it is in their best interest to have 2 minimum.
But some breeders/glider lover owners have posted that some of their gliders
won't take a pair, and every introduction ends in a fight and they have some
that just live alone.
every time we have done an introduction with a small number it has gone
excellent, gliders love to have other glider with them in our experience.
as you add gliders to the colony it gets harder as some resist additions.
presently I have 6 gliders in our colony and gus refused the addition of 2
more, he is the alpha and wants nothing to do with more, after 2 failed attempts
with the rescued gliders we had to rehome them.

My opinion in the end....
some glider live alone and do fine, reported by many owners, but they live
together in the wild and seem happiest that way, someone to interact with and
sleep with to keep warm, NOTE: gliders conserve energy by sleeping together and
conserving heat, very important in the wild.
What is the difference for you between one and two??? I have six, I put out
alittle more food, I put out lots of water, I have to clean the cage and give them
toys and attention. SAME as if I have one. maybe more potential for vet bills and
more food costs. cutting nails takes 15 minutes longer every 2 weeks.
you will have two loving gliders, and if one is not as loving, you will have
more chance to get one that bonds better. with only a slight increase in a food
bill and more chance of having happy gliders.
so I recommend two or three if you can afford them.

I have a rescue who overgroomed like crazy from being kept single.

www.sugarglider.com/glidergossip/photo_album_view.asp?cname=Papaya+Overgrooming&mid=20933&cid=5204

After he got friends he stopped and is much happier. On days when I don't have as much time to play with them they have each other so they never get lonely.

I wouldn't recommend ever keeping a single glider unless it has a past of killing cagemates.