The stadium is already there, all we need is for the AFL to schedule a couple of games against low drawing interstate clubs and we are laughing.
20k at Moorabbin would make more money for the club than 30-35k at Marvel but that would need the AFL and corporate cronies agreeing to forego direct revenue in favour of the Saints getting it.
That is the issue though, there should be no such thing as a "low drawing interstate club", if there truly are not too many clubs in Melbourne, they should be able to attract their own supporters to a game, no matter who the opposition is. It can be done in Adelaide and Perth consistently.