I know what you mean about the betta bug...got bit bad myself...1 and half yrs ago, I got my dtr a betta in a 2.5gmini bow. That was it...now I have about 20 bettas (had tropical fish most my life, but never a betta!) and many are from Thailand. I have 2 sororities and four Kritter Keepers that are permanent homes for bettas. I use sponge filters but easier for me since I hooked them up to same air filter. I use the Petco submersible filter because its reliable, available locally, and adjustable. Currently my keepers get sunlight from a window part of day, which seems enough for floating plants such as dwarf water lettuce, Asian bogmoss, salvia, and Amazon frogbit, and duckweed. I plan to attach a 4ft shoplight above the keepers so they can have more aquatic plants since bettas seem to love a home with lots of real plants, just like me!
Anyway, I find that glassware and candle cups and holders make good and cheap homes for bettas.