@aaronpk If it's a gift card that can be used to purchase a product from anyone (not just from the seller asking for the review), then that's different. However, they may have made a $200-300 profit on the $500 sale. Reinvesting part of the profit into reviews for a new-ish listing can create a competitive advantage that can pay off well over the longer term. Even if they break even or have a small loss, it can be an effective "loss leader" strategy. https://en.wikipedia.org/wiki/Loss_leader
@aaronpk It sounds like a lot to “pay” (it doesn’t cost them $150) for a review, but the ROI depends on the price of the item being sold. Good reviews are a necessity for a successful listing on Amazon and they will affect sales performance for years. However, the technique is risky for them because it violates Amazon’s ToS and could cause them to lose the ability to sell on that platform.
That’s awesome. I actually use Quill daily for posting and testing. I ended up finding omnibear which does most of what I want. It even detects if a site supports webmentions and displays a “W” during the reply. Omnibear definitely leaves a bit to be desired, but does the job. Is your Quill bookmarklet public?