Various merchants via eBay take up to 88% off select new and open-box unlocked phones, with prices starting from $28.99. Plus, these orders qualify for free shipping.

Buy Now

A couple of best bets:
-- Unlocked LG C195 GSM Quadband Smartphone for $29.99 ($50 off)
-- Unlocked HTC Desire 610 Android Phone for $99.99 (pictured, low by $10)

Note that warranty information is available on individual product pages.