Everyone here says they're so expensive, I would beg to differ! I have found goodwill and craigslist to be huge money savers for me, but because some here have disgust or bad experiences over such things, I will tell you how I gave my betta a brand new home for cheap!
Kritter keeper 2 gal: $10
Fake plant: $2
Rock cave: $1
Moss ball: $3
Her tank is a jungle! I will post pictures soon. Heaters for that size are $10 generally. Thermometers are $2 (which I get tomorrow). I could have gotten this cheaper, too. Filters can be found for $6. I could have done without the fake plant. I could have silicones my own rock cave from the rocks as her substrate.
I paid $35 for everything (minus heater, including thermometer) and $3 could've gotten me a 3 gallon. If I had done everything cheaper would be at $25.
I promise you all there are great deals out there if you LOOK! The fish deserve it! Plus, fully lighted, filtered, decorated tanks can be found for $20+$30! Give your fish the things they deserve-- and need!!!
How did you set up your tank on a budget?? Lets give ideas so others can find a way to satisfy their bettas needs on a budget!(: