I do agree this is a good topic to bring up, its good to point out to people that bettas can cost more money than one aspires and all.
Yes, I have 11 bettas as of now. I do water changes weekly, and on the guys in just a one gallon, twice a week. Its no problem for me, as I have other tanks to clean, also. No one is in anything less than a one gallon, and everyone is being moved up to a 2.5+ of their own at christmas.
I knew bettas can live 2+ years when I bought them, and I treat everyone with as much care as all my other fish. I always have money put back for all of my pets, for emergencies such as diseases and all, so I do have the money if one falls ill.
I treat my fish just as if they were one of my rats, dogs, cats, etc. They are a big part of the family^^.