Don't sugar gliders do best in groups?
Sometimes, but they can do great alone as long as you give them enough attention. A sugar glider I had named Billie was a great pet, I spent 2 to 3 hours every night with him and the rest of the time while I was sleeping I would let him run around my room all night, my room is very secure so there was no possible way for him to get out. When my friend took Billie in she had another female sugar glider, well Billie killed her sugar glider ripping her apart. Usualy sugar gliders do well together but I geuss Billie was not like that sadly.

There's also those excotic mice that look like kangaroo's,

Also have you heard of Richardson Ground Squierls?

Oh there's also small birds lol, you can buy hand fed finches in beautiful colours, they'll follow you around and can live from 5 to 10 years old depending on the breed and how well it's taken care of, not loud and easy to afford, they just need a small cage, a few toys, seeds and water. If you want you can pair 2 together.

You can buy excotic finches.