I'm looking for some successful models of ebooks in pdf format...

Group,

Do anyone know of any successful ebooks, that is actually selling on the internet, that is done in pdf format?

I'm looking for some successful models so that I can see that selling ebooks is worth it. I'm just being conscious of my time so that I don't wind up making a mistake, based off of all the hype that could be surrounded by the e-manual selling.

I need to see the numbers before I start this particular journey of emanual development.

Thanks,

hilton