I am the founder of Chrome-Stats. We just launched a marketplace for buying and selling Chrome extensions (https://chrome-stats.com/marketplace/forsale). Listing is 100% free. You can choose to reveal the listing to everyone (more visibility, but may have more spams), or to our premium members only (less visibility, but more targeted to serious buyers).

If you are interested in acquiring Chrome extensions, or selling your unmaintained extensions, then give it a try.