I created two ebooks for my sites here at bellaonline a while back but had really been struggling to come up with an info product for my own fitness site.
I finally eliminated all the distractions and got busy and just completed my info product yesterday. It's 130 page workout plan for a niche female audience that includes tons of workouts, healthy fatloss meals and success tips too. I already give away a free ebook on my site to newlsetter subscribers so this ebook will be around $15. I plan on offering it in other formats too.
The biggest challenge will be deciding between ejunkie or Payloadz or bytecommerce. I found this article:
13 Options for Selling Digital Products On Your Website that was very helpful but still undecided about how to process transactions.