Tropicallvr

The only place you can possibly find corms is from India where the seeds are sourced, and that will cost a bit. Your best bet is going to be seedlings on ebay in the next year or two. Otherwise your going to have to germinate some yourself because they are brand new on the market within the last 6 months.
Musa sikkimensis helens hybrid has been out for over a year, and it's a really rare to find it for sale, but ebay would probally be the first place it is offered.