I Built a Price Monitoring Bot That Saved My Client $12,000

The phone call that started everything Last year, a small e-commerce owner called me in a panic. His competitor was undercutting him on 200+ products — sometimes by just $0.50 — and he was losing sales every day. He'd been checking prices manually. Every. Single. Day. For 200 products across 3 competitor sites. I told him: "Give me a weekend." Here's the bot I built, and how it saved him $12,000 in the first 3 months. The architecture (surprisingly simple) ┌─────────────┐ ┌──────────────┐ ┌─────────────┐ │ Scraper │────▶│ Price DB │────▶│ Alert System│ │ (Python) │ │ (SQLite) │ │ (Email/TG) │ └─────────────┘ └──────────────┘ └─────────────┘ │ │ │ Runs every 6h Stores history Sends alert if via cron + calculates diff price drops >5% Three components. No cloud. No database server. Runs on a $5/mo VPS. Step 1: The scraper import requests from bs4 import BeautifulSoup import sqlite3 from datetime import datetime def scrape_price ( url , selector ): """ Scrape price from any page using CSS