Using an AI Browser Agent to Monitor Facebook Marketplace and Craigslist for Underpriced Items to Flip
Originally published Sep 10, 2026 — Greg Isenberg
Greg Isenberg · GPT-6 Astra: How I'd Make Money With It ↗
Set an AI agent with browser/computer-use capability to continuously watch Facebook Marketplace and Craigslist listings in your city for items (cameras, furniture, bikes, etc.) priced noticeably under market value, and have it text you immediately with a link when it finds one, so you can buy and resell the item for a profit.
Discussed as one of several practical prompt ideas for a new AI model on a podcast, framed as especially useful for people who want to make a few hundred dollars a day, including younger people who can't find traditional jobs right now, an AI agent does the constant scanning a human would otherwise have to do manually.
Someone in a city with active local marketplace listings and available cash to buy items on short notice, comfortable acting quickly on alerts to beat other buyers to underpriced listings.
Marketplace arbitrage/flipping itself is a well-established side hustle, and using an AI agent to automate the constant watching is a reasonable extension of that. This was mentioned briefly as one of several prompt ideas in a wide-ranging discussion, not demonstrated live or with results shown, so there's no verified evidence of how well the automated monitoring performs in practice, and competition for the same underpriced listings will increase as more people use similar bots.