A friend of mine has set up a facebook page where they are advertising a calendar for charity. He asked me for advice as to how they could possible "sell" these calendars via facebook - looking for something like a buy now button on facebook and select quantity. Payment processing can be taken care of by PayPal or any other reputable 3rd party. I have very little experience in this area so would anyone have advice for me regarding this - is there a way of accomplishing the above via facebook and if so, how? Any advice would be great.