You should go and look through all the back posts in the E-Commerce forum here.
You're absolutely right that accepting credit cards online can be an expensive proposition, which is why all they turnkey sites charge high transaction fees.
If you're only selling one product, it's going to be hard to justify the costs associated with setting up a merchant account and handling secure transactions.
You may want to check out GoDaddy , if you haven't already done so.
You may also want to check out Amazon.com. It looks like they have a way you can sign up as a seller. I have never used it and it looks expensive, but you might weigh that against the cache of being able to tell your customers that your book is available at Amazon.