CowBoom offers the used Sony PlayStation Vita WiFi System, model no. PCH-1001, for $119.99. Coupon code "Vita20" cuts it to $99.99. With free shipping, that's tied with our December mention as the lowest total price we've seen for this model. (It's also $84 less than another used unit and $115 below the best price we could find for a new one.) It features a 960x544 multi-touch 5" OLED, multi-touch pad on the rear of the device, dual analog sticks, and front- and rear-facing digital cameras.
Note: No warranty information is provided. Also, this used unit is a grade 4 and may be missing parts or accessories and have significant scratches or scuffs.