The bettatalk strain catalog has "Holy Grails" which are pure white and extremely rare. Seeing how there is only one line of double tail opaques (white) I'll have to spend the $100 bucks on a pair. But I enjoy the hobby.
Not a whole lot of money. And what I do earn is usually spent on the stuff I need to breed. But I will hopefully be breeding some nice pure white bettas (single tail and double tail) by next year :))