The Apple Store offers a selection of factory-refurbished Apple iMac desktops, with deals from $929 and free shipping. These desktops come with a 1-year Apple warranty, the same as new iMacs. A couple of best bets, with lows compared to new models:

• Refurb Apple iMac MF883LL/A 21.5" Haswell i5 Dual 1.4GHz for $929 (pictured, low by $71)
• refurb Apple iMac MMD095LL/A 27" Haswell Core i5 Quad 2.9GHz for $1,399 ($400 off)