hey Emily ,
I just got a bunch of little gobies at GA. they kind of disappeared in my tank, but in a smaller tank you would see them more often. they are not expensive, they stay small and they have cute personalities.
check out the yellow clown goby (Gobiodon okinawae), hectors goby
(Amblygobius hectori), red striped goby (Trimma cana), black clown goby (Gobiodon strangulatus), there are a bunch more there, all of them would be fine for your tank.