"Blish is the easiest place to buy or sell digital content. As a buyer, you can purchase ebooks, photos, how-to guides, clipart, music, sound loops, video, design templates, any type of digital content. As a seller, you can post digital content that you own and make money."
The blurb says it all. I checked the site, and their sign-up process for sellers is what's not the easiest part. It's no "do-it-yourself," the would-be seller has to discuss the idea via e-mail. Slightly old-fashioned, web 1.5ish, but still it's a marketplace!
Buy & Sell Digital Content
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Hydrogen Fuel Cell Aircraft
Simplified Security Cameras
Heritage-Inspired Seed Packaging