Other World Computing discounts a selection of used Apple Mac Pros, with prices starting at $575. 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 couple of best bets:

• Used Apple Mac Pro Quad 2.66GHz Xeon Workstation w/ 4GB RAM for $575 (low by $229)
• used Apple Mac Pro 8-Core 2.66GHz Xeon Workstation w/ 8GB RAM for $1,079 (pictured, low by $140)