Pro tip: don't buy clippers off Facebook Marketplace to save a buck
Dropped $85 on a used Wahl Senior from some guy in a Target parking lot off I-35, and it died mid fade on a paying client yesterday. Opened it up and the blade was shot and the motor was packed with hair from what looked like a dog groomer. Save your money and buy new from a real supplier, your chair time is worth more than the discount.
Been there with a used Oster A5 I grabbed for $60 off Craigslist years back. Same story, motor full of crud and the blade was dull enough to pull hair instead of cut it. What most folks don't realize is you can't just swap a blade and call it good, the motor itself wears out and replacement parts cost almost as much as a new unit. Ask the seller to run it for a full two minutes before you hand over cash, and pop the blade off to check for rust and packed hair. If they won't let you test it, that tells you everything you need to know.