Interesting, I’m not big on AI but I have thought often it would be nice to have an ‘agent’ that monitors ebay or other classifieds sites for items based on a natural language description.

Something like “I want an old mini PC to use as a home server, it should have roughly these specs and cost under this amount”, and then an LLM would run some searches every day, parse the results and send me a message if something comes up.

It’s pretty easy to get alerts for when items are available for a certain price if you know the exact item you want, but on eBay and classifieds sites, I usually just want something in a rough ballpark, and the best way to find that is come back and check every day looking through searches.

I don’t really see any value in having the AI do the purchase itself though.

The purchasing itself can important for it to jump on a great price. Maybe it finds what you're looking for at 1a while you're sleeping for example. Also if this were a business and you were going to resell it the AI could also create the listing as soon as the item is purchased.

I would expect a naive implementation would give you a "least worse" option everyday and can't judge when it is "good enough"

Afterall, that's what most people would be when asked to make decisions for others without context.

Making the agent understand your requirements would be quite a bit of work.

I essentially do this but on a state surplus auctions site. It's just a scheduled action which searches for something, e.g. old Lego kits, once a week. Usually nothing comes up but at least once there are kits I know about it.