Zotac's fanless ZBox CI327 mini PC now on sale starting at US$160
Zotac has a line of passively cooled mini PCs known as the ZBOX series. Announced back in January at CES, these PCs are small, silent, and fairly affordable for what you get. Pricing for the ZBOX CI327 has just been made official: a bare-bones Celeron N3450 kit is available for US$159, while a i3-7100U and i5-7200U kit will cost you US$325 and US$392, respectively.
That ends up being a fair chunk of change once you start speccing up the CPU, but you do get Zotac's fairly nice case with a power supply, 802.11ac WiFi, Gigabyte Ethernet, HDMI 2.0, DP 1.2, and of course USB 3.0 Type-A and Type-C. You will need to add your own memory and storage (and OS!), however. If you're looking for a home theater or compact office PC, this might be worth your time.