Newegg via eBay offers the ASRock Z170M Extreme4 LGA 1151 Intel microATX Motherboard for $99 with free shipping. Outside of the price below, that's $26 off and the lowest total price we could find. It supports up to i7 processors, 4096x2304 resolutions (4K UHD), and 64GB RAM. It features three PCI Express 3.0 x16 slots, six Serial ATA 6Gb/s slots, one M.2 socket, four rear USB 3.0 ports, USB 3.1 Type-A and Type-C ports, HDMI, DVI-D, and Gigabit Ethernet.
A close price, Amazon charges $99.99 with free shipping, however it's out of stock until April 11.