How to Create a Coupon Code?

Hi,

I am going to be releasing a free-for-limited-time ebook soon. It's a unique activity book for kids on my upcoming parenting site.

I have a few questions about how to do this best.

I will feature the ebook on my home page, with a blurb: "subcribers get it free!" and "Subcribe here!"

In order to increase the perceived value of the ebook, I'd like to set up a paypal or any shopping cart page where the free downloaders go. The page says the ebook costs $19, and the first email with the link to this page (i'll be using aweber if that matters) gives them code XYZ to enter, which will make the ebook free.

Wouldn't you rather enter a promo code into a site thereby paying $0 instead of $19... rather than downloading just another free ebook? I believe it would make it seem to be a better value!

Also... once my list builds up, I will start charging for the ebook in the future.

Also, I will release the info about the free ebook to different webmasters, with different codes, so that I can track how much traffic each webmaster sends me. (but I suppose that does not help if a certain webmaster has a very small list, yet one subscriber forwards the offer to a million friends... I still won't know who my promoters really are)

How do I do this? Is paypal the simplest? My site is hosted with Thirdsphere, they have 2nd checkout amoung some others. I'm very new to this.

What is the simplest way to implement this idea?

Thanks in advance!