Other World Computing offers the OWC Data Doubler Optical to SATA Drive Converter Bracket for MacBook and MacBook Pro (pictured), model no. DDAMBS0GB, for $44.99 with free shipping. (Newer Galaxy Distribution Company via Amazon charges the same.) That's the lowest total price we could find by $22. This bracket allows you to add up to 1TB of internal storage to your MacBook or MacBook Pro in place of the optical drive. It comes with a 5-piece toolkit, screws, and an installation guide.

Also available from Other World Computing is the OWC Data Doubler SSD/2.5" Hard Drive installation Kit for Mac mini, model no. DIYIMM11D2, for $34.99 with free shipping. (Newer Galaxy Distribution Company via Amazon charges the same.) That's $10 off and the lowest total price we could find. This kit allows you to add a 9.5mm or smaller 2.5" SATA Hard Drive or Solid State Drive (not included) to your 2011, 2012, or later Mac mini. It also comes with a toolikt and installation guide.