Yes there are no way Bettas and Goldfish can be housed together.
However I had my Betta in a tank with Platies Mollies and Corydoras catfish. The Platies and Corys were fine but I ended up having to take the Betta out because the mollies were nipping at his fins.
I would recommend platies though. They were great with the betta.
Also you could get a couple African Dwarf Frogs.
But this all depends on how aggressive your Betta is
Me: You need to wait until you're grown up, have a steady job and a house before you can get a 120+ gallon aquarium.
Myself: But I really want some some Bala Sharks, Tiger barbs and a red tailed black shark! That would be awesome!
Me: Stick to Bettas at least until you're out of college.