I built an AI that tells you what any item is worth — here's how and why

A few months ago I was trying to sell a second-hand PlayStation. I spent 45 minutes searching eBay, scrolling Facebook Marketplace, trying to figure out if €280 was a fair price or if I was leaving €80 on the table. That's a solved problem. It shouldn't take 45 minutes. So I built ValueScan — an AI-powered item valuation tool. You describe an item or upload a photo, and it gives you the retail price, resale range, a recommended listing price, and exactly where to sell it. In about 10 seconds. Here's what I built it with, what I learned, and where it stands today. The tech stack Frontend: React 19 + Vite. Nothing exotic — just a chat interface with a valuation card renderer. The whole UI is one App.jsx file which I probably should have split up but here we are. AI: Google Gemini 2.5 Flash via a Vercel serverless function. I chose Gemini over GPT-4 for two reasons: vision support for photo uploads is solid, and the cost per token is significantly lower for a use case that generates long