Doing the sums quickly on a scrap of paper, James Cundall estimated the Sydney season alone of Singin' in the Rain would cose $10 million to $11 million to stage.  Multiply that by every major city in Australia and then a proposed Asian tour and the staging of a musical of this calibre becomes a very expensive -- and risky -- affair.     A number of failed productions in recent years is testimony to the stakes involved but Cundall, a former banker, is confident a product such as Singin' in the Rain can do the business.     "My business is really no different from running a bank but we do have a far more emotional product," he said.  "And we run a big business -- this year we sold in excess of $50 million in tickets across Australia and Asia."     Despite the cries about the death of the musical, Cundall believes it is a viable entertainment option, given the right circumstances.     "I think the musical climate is good," he said.  "Everyone talks about this year (being slow), but everyone was being very sensible, trying to stay away because of the Olympics.  I think a lot of us felt that, despite all the pre-Olympics publicity, when the circus came to town everyone was going to embrace it and you can't fight against the biggest show in town.     "Everyone thought that musical entertainment was dead but good shows will always win out.  Everyone talks about there being too many revivals and, yes, we do use a lot of revivals because people know they're safe, people are going to get a good night out.  But there are new shows coming out too, like Mamma Mia.     "You can't cheat an audience -- you can't deliver anything but the best quality."