As long as you don't keep the betta in one of those tiny plant pots, they make a good and pretty pet. I had one in a tank with some other fish and they did fine, they are only territorial with their own male kind. You can buy a small corner tank in walmart with a filter and hood with light for $10, I have one outside in my shed, and if you lived closer I would give it to you! They hold 1 gallon, big enough for a goldfish and an algae eater or something, and in fact that is exactly what I had in it - a nice 3 inch or so goldfish, and about the same size algae eater. Kids looked at them for about a week, then never looked at them again, so I gave them away about a year ago, to a person with a 4 foot tank - Goldy is now 6 inches! and has a great life!
Just want to clarify (and I don't know why this kind of thing irritates me, but it does!) that the Siamese fighting fish or BETTA splendens, is not called a BETA!! it is pronounced bet uh, not BETA like the greek letter ARGH!