If you don't already have a PayPal account, I'd suggest to get one. It's free and it's the safest way to buy anything at all over the internet. Once your account is set up, you don't even have to transfer money into it, as it will just automatically deduct the required amount directly from your debit card for you. This protects you from having to give your bank details to anyone ever. Plus PayPal will retrieve your money for you in the event of anyone trying to rip you off. :)