I would suggest some of the smaller tetras and rasboras. There are many small schooling fish in these groups. Rasbora hetramorph or espei are nice looking schooling fish along with the neon tetras, ember tetras, green fire tetras, glolight tetras, even some of the smaller rainbows would be nice. There are just too many fish to cover and they should be pretty inexpensive and hardy. Just take a real good look at the tank you want to buy from and make sure everyone looks healthy. Do take a look at the adult size of the fish you pick out. Some of the fish sold in fish stores get way too big for the aquarium and they grow fast.
I hope this helps you

I hope this helps you