There are many chipsets with the LGA 1151 socket, including the Z170, B150, H170 etc. The only chipset that allows overclocking would be the Z170 chipset, which you should get since you are getting a overclockable CPU. The other chipsets I mentioned are cheaper (sub $100 range) but lack some of the features the Z170 has. Even with the same chipset, there are higher quality motherboards (more expensive) and lower quality motherboard (cheaper). The higher quality motherboards have more features such as better power delivery to allow more overclocking, better NICs, better sound cards, more PCIe slots, etc. The motherboard you would need would depend on what you are using it for.
A $60 motherboard would be "good enough" for you. You would not be able to overclock if it's not a Z170 chipset (so the overclockability of your CPU is wasted), it probably doesn't have SLI and/or CrossFireX support, so you would be limited to only having one GPU. The PCIe lanes could also be slower, so higher bandwidth PCIe cards would take a performance hit.
The speed of the RAM doesn't have to correspond to the motherboard's rated max speed. The RAM would run at the lower speed of the two (e.g. if your RAM was 3000MHz and your board only supports max of 2400MHz, it would run at the lower of the two, which would be 2400MHz). This also means you are wasting some of the power of the RAM if you buy a lower end board. You would also want to check with your motherboard manufacturer's manual to check if the RAM is compatible with your board.