You can absolutely use websites like eBay and Etsy! Try listing some items and making a professional Facebook page for yourself with a link to your eBay/Etsy pages. Then share the information with friends and family and get them to spread the word to people they know. Also, make sure that you have detailed descriptions and multiple pictures with anything you list online. This will help your listing show up in keyword searches, and you are more likely to sell something if the buyer knows a lot about what they are looking at.
This is a way to help you create a website for your own product that essentially integrates with Clickbank to make selling this product easier. I think this is a cool idea, and for folks looking to create their own digital product, this would be a worthwhile investment. But remember, you're now paying $47/month for CBU members area ($564 per year), PLUS $594 for the builder. Your yearly cost of business operation just jumped to over $1,000. Also, remember that this might lock your site into their builder, so if you decide to change to outside hosting at some point, I'm not sure how that process goes.
With drop shipping, you’re effectively partnering with a manufacturer or wholesaler to sell their products. This way, you don’t pay upfront costs to buy inventory, aren’t sitting on unsold items taking up expensive warehouse space, and don’t have to deal with shipping the products yourself. You simply create your site, fill it with drop shippable products, and drive in customers, with almost everything else done for you.