Yes, you need to buy the Picaxe chips, you cannot simply burn on the bootloader/Basic interpreter. Rev-Ed its revenue from that, so the bootloader/Basic interpreter is not publicly available. That said, the Picaxes are only marginally more expensive than the Pic microcontrollers they are based on, so unless you use a large number of them, that's probably cheaper than building or buying a Pic programmer anyway (and less work, too).
I don't think a credit card is mandatory to order Picaxes. Where are you located? At least one of the distributors also accepts Paypal (
www.paypal.com) as payment, probably several others, too:
http://www.world-educational-services.com/
You can fund your Paypal account in a variety of ways, including checks and direct bank transfer.
Wolfgang