Reforger via Rakuten Shopping offers the open-box Logitech Ultimate Ears 600vi Noise-Isolating Headset in Dark Silver, model no. 985-000121, for $24.95 with free shipping. That's $14 below our September mention and the lowest total price we've seen. (It's a current low by $15 for a refurb.) They feature an in-line microphone with controls, frequency response of 20Hz to 20kHz, five sizes of silicone tips, two Comply foam tips, and protective case.
Of note, no warranty information is provided.