If you are going to buy things on the web then you will need some sort of payment card. If you don't have a credit card then check if your ATM card doubles as a Maestro or Visa payment card. Credit cards are preferable because of the chargeback options if there are problems with the purchase.
If you don't have a bank account then there are a number of suppliers who will sell you prepaid payment cards, at a handsome commission.
If you are set on using Bravenet to register a domain name, candy's answer pretty well covers the possibilities.
I did a Google search for:
"domain name" "money order"
(with the quotes) and got many, many matches. The first one I checked included the sort of notes I had expected:
"Orders placed by personal or business checks are not processed until bank clearance. You should allow up to 2 weeks for postal mail and bank clearance. Orders placed by bank or certified check or money order are processed upon receipt. Allow up to 1 week for postal mail delivery."
I believe on that particular site, the info was meant for users within the U.S.
Many firms will use credit cards and perhaps PayPal only, because this allows them to automate the process. Manual processing of orders is something they generally would want to avoid, for many (obvious) reasons.
