I built https://hnrecommends.com a little while ago. It's the start of a curated list of Hacker News recommendations. I'm adding recommendations and products daily. It's made a few dollars from affiliate links so far.
> I'm adding recommendations and products daily. Do you add the recommendations manually or do you use a crawler/API to copy the comment? How automatic is it?
Finally, I have two suggestions: You're only selling to people in the US. Maybe you could also add links to other Amazon domains (or use a service like geni.us)?
And how about linking back to the comment thread? Sometimes, a comment only makes sense in its context, and I couldn't find a link back.