Massdrop offers the Optoma NuForce uDAC5 Portable DAC and Headphone Amplifier in Silver for $99.99 with free shipping. That's the lowest price we could find by $59. Deal ends December 28. This USB-bus powered DAC features:

ESS Sabre 9010 K2M DAC chip

support for high-resolution PCM, DXD, and DSD256 playback

USB input

coaxial S/PDIF, RCA stereo, and 3.5mm outputs

Note: It's expected to ship on January 18, 2019.