: Specialized retailers like iFixit and OWC (MacSales) offer DIY kits for internal upgrades, including batteries (approx. $80–$135 ) and SSDs.
: Typically ranges from $20 to $70 on Mercari or eBay. buy osx
For any Mac made in the last 10–12 years, you typically do not buy a physical "piece" of software. : Specialized retailers like iFixit and OWC (MacSales)