When recently buying the Intel Pentium G4400, a ~$60 Skylake dual-core processor, for Linux testing I was also looking for a Skylake motherboard that wouldn't cost an arm and a leg. The motherboard I ended up pairing for this Pentium G4400 in the test lab was the Gigabyte GA-H110M-A, a micro-ATX board using Intel's H110 chipset.
Compared to the Z170 chipset and even the H170, the H110 chipset has less HSIO lanes, just x6 PCI Express 2.0 lanes, one PCI Express x16 slot, no support for CPU overclocking, support for only one DIMM per the two memory channels, only four Serial ATA 3.0 ports, up to four USB 3.0 ports, no Intel RAID support, only support for up to two displays rather than three, and more. With the H110-based motherboards you're losing a lot, but the price of such motherboards is much lower than the Z170 or H170.
For my purposes of pairing the GA-H110M-A motherboard with a $60 Pentium Skylake processor, the lack of overclocking and cutdown other features was fine by me for assembling an affordable Linux system just to be used for benchmarking to complement my higher-end Intel Core i5 Skylake systems with Z170 motherboards.
This Gigabyte motherboard currently retails for just $55 USD on Amazon.com. There are tow DDR4 DIMMs, one video output (HDMI 1.4), Realtek Gigabit Ethernet, one PCI Express x16 slot, two PCI Express x1 slots, four Serial ATA 3.0 ports, two USB 3.0 ports on the rear panel, and four USB 2.0 ports. It's really a barebones motherboard but its cheap and gets the job done.