You buy used parts cheap at self-service (U-Pull) yards, where you pull them yourself at a flat posted price, and resell them to people who need them. Your profit is the sale price minus the yard price, platform fees, shipping and supplies. The money is in knowing which car and which part before you pull; guessing is how people lose money.

The whole business in 9 steps

1. Set up your selling accounts (eBay, Facebook Marketplace) and a simple money system.
2. Learn the rules: what you can and can't legally sell.
3. Check yard inventory for fresh cars and price the parts against recent sold prices.
4. Pull the right parts safely, with the part numbers photographed.
5. Clean and test them.
6. Photograph them well.
7. List them with exact part numbers and fitment.
8. Pack and ship (or sell locally), then handle any returns.
9. Track every dollar and hour, and reinvest in what earns most.

Three ways to run it

Guessing vs. knowing. One forum poster paid $43 plus a $3 core for a junkyard sensor that sold new online for about $30, a loss before gas (BITOG). On the other side, ChopBot's own estimate for one 2009 Maserati at a Virginia yard: its four Brembo calipers priced about $87 at the yard, against recent eBay sold prices of about $1,002 for the two pairs. After the eBay fee (about $137), estimated shipping ($70) and the $87 yard cost, that leaves roughly $709, with ChopBot estimating about 1 hour 20 minutes of work. That's a best-case find and an estimate, not a typical or guaranteed result, but the gap between those two stories is the whole lesson.