MacMall offers the refurbished HP Envy 27 Intel Skylake Core i5 2.2GHz 27" All-in-One Touch Desktop PC, model no. M9Z75AAR#ABA, for $705.99 with free shipping. That's the lowest total price we could find for a refurb by $44. (It's also $434 under the cost of a new one.) It features an Intel Core i5-6400T 2.2GHz Skylake quad-core processor, 27" 1920x1080 (1080p) LED-backlit touchscreen display, 12GB RAM, 1TB hard drive, webcam, 802.11ac wireless, Bluetooth 4.0, media card reader, and Windows 10 Home 64-bit.
Of note, no warranty information is provided.