: If you are fixing an older machine, ensure you get a Retail Version (usually a purple "space" disc) rather than a grey "Machine Specific" disc, which may not work on different models. Essential Pieces for Your Mac

: Recent versions like macOS Tahoe are free downloads via the Software Update section in System Settings.

: Specialized retailers like iFixit and OWC (MacSales) offer DIY kits for internal upgrades, including batteries (approx. $80–$135 ) and SSDs.

: Around $130 at retailers like eBay - pcmonde.

If you meant a specific accessory or replacement part to go along with your Mac purchase: :

Physical retail "pieces" of the operating system are mostly used for restoring older PowerPC or early Intel Macs.