A price watcher for the thing you want

Level 2: two to three weeks, real architecture. Use with: automate-a-task, use-an-api. Resume line when done: Built {project_name}, a scheduled price monitor with push notifications — ran unattended for {n} weeks and caught a {pct}% drop

Brief

There is a thing you are saving for, and you check its price by hand every few days. Build a script that checks it on a schedule and sends you a push notification when the price falls below your threshold. Prefer an official API where one exists (eBay and Best Buy both have free developer APIs); if the store has none, fetch the public product page gently: once or twice a day, honoring robots.txt, with a User-Agent that names your script. Notifications go through ntfy.sh (free, no account) or a Discord webhook, and the schedule runs on GitHub Actions cron (free on public repos). The bot alerts you; it never buys anything.

Personalize

• A thing you genuinely want. Real threshold, real budget. If the alert fired tomorrow you would actually act on it. Watching a random product teaches you nothing about whether the bot works.
• The store you would really buy from. Check whether it has an API or a price feed before deciding to parse HTML.
• Where you want the ping. Phone notification via ntfy.sh, or a message in a server you already read. Pick the one you will see within an hour.

Milestones

1. Check the price by hand for four days and log date, price, and how long the check took. This is your baseline.
2. Write a script that fetches the current price once and prints it. If there is an official API, use it; if not, parse the page and set your identifying User-Agent.
3. Store each check as a row (date, price) in a CSV or JSON file committed to the repo, so you build a price history.
4. Add the threshold rule and a test notification through ntfy.sh or your webhook. Trigger it manually with a fake low price.
5. Schedule it: GitHub Actions cron, twice a day at most. Secrets (webhook URL, API key) go in repo secrets, never in code.
6. Add failure handling: if the fetch breaks or the price parses to nothing, notify you about the breakage instead of going silent.
7. Let it run for a full week without touching it. Resist checking the price by hand.
8. Chart the collected history (a simple generated PNG or a table in the README) so the repo shows real accumulated data.
9. README: what it watches, how the schedule works, what you would change to watch a second item.

Done means

• The watcher has run on schedule, unattended, for at least a week
• The run history and the committed price log prove every check
• A real notification reached your phone (threshold or test)
• You have stopped checking the price manually
• Fetching is polite: at most twice daily, robots.txt honored, script identified in its User-Agent
• All secrets live in repo secrets or env vars, none in the code
• The bot has no ability to purchase, only to notify