Depending on your topic, ebay can actually bring you decent sales. I'd suggest doing it as a second source for income at the very least.
This all really depends on your market. The problem with clickbank is that you don't always find affiliates interested in your product, which makes the whole system pointless. Make a judgement based on your product, and just try some options out! There's so many ways to market ebooks anymore.
I'm finishing up another ebook now myself, and was considering taking the route of the passworded site instead of the PDF. Now I just gotta find out how to do that......