Ted here from Shopify! I see that you posted this query some time ago but I just said I'd pop in and update this thread in case anyone is looking for the same response.
It's not possible to pay your Shopify invoices through bank transfer, however, you can now pay with Paypal instead. While a credit card is still needed, a good workaround would be to add money to your Paypal Wallet. A great breakdown of how Shopify charges can be found here if you would like to take a look.
Were you able to sign up for a store previously? If you've any other questions about the platform please let me know!
Thanks a mill,