I used to have a double tail betta. Double tails are by far some of the best looking ones. One thing I can't understand is why people keep them in tiny cubes, mine got a whole fish tank to roam.
Mrs I, contact Jodie-Lea at WestSide Pets, in Taringa (Brisbane) on (07) 3870 7829. She has the best Bettas i've seen. If you check out aquabid.com you can bid on fish from overseas and have them imported through her. Seriously check them out, if you're going to put the effort into breeding Bettas you might as well breed some that will get you some $$ when you sell them on again. Think Plakats (short finned - my fave) Halfmoon, Spade Tail and Double Tail. I'm finally down to one male Halfmoon Plakat, an opaque solid white. At one stage i had over 50 adults around my room (but then i got into snakes... hehe) after going through Jodi i never even bothered looking at the fish in the pet shops, they're pretty much just a juble of anything that the breeding didn't think worth keeping, thats why you get the mishmash of colours and fin types. dont get me wrong i still love them, but after getting into halfmoon coppers, with the females better looking than the boys, you cant really compare them! careful, its addictive