It would for sure be cheaper to bring in all new girls, but their audience would take a huge hit.
Bravo is no longer here for paying the big salaries. Unless you're of value to them.
That's why I don't really see them jumping on Porsha's offer to return. What exactly is she bringing to the table to be the highest paid housewife?
The ONLY way that would be worth it is if Falynn came back too.