Tanga offers the open-box JBL Flip Bluetooth Wireless Speaker in Black, model no. JBLFLIPBLKAM, for $49.99 with free shipping. That's $20 under the lowest total price we could find for a new one today, although we saw a refurb for $10 less a month ago. It features 40mm drivers, a built-in microphone, and Li-ion rechargeable battery with up to five hours of run-time per charge.
A 30-day warranty applies, but it's unclear who covers it.