Other World Computing discounts a selection of used Apple Mac Pros, with prices starting at $649. Plus, all orders qualify for free shipping. Each item is covered by a 90-day OWC warranty. Note that for some models, available quantities may be limited. A few best bets, with comparisons to refurb units:

• Used Apple Mac Pro Quad 2.66GHz Xeon Workstation for $649 (pictured, low by $334)
• used Apple Mac Pro Quad 2.8GHz Xeon Workstation for $995 (low by $217)