Go to newegg and look at intel motherboards.
Filter on ITX and lga1151. you can sort by price.
All will do the job.
You might want to pick one with wifi if you need wifi. USB wifi is not that good and there will be only one pcie expansion slot.
All will have decent onboard audio.
If you will use integrated graphics, then they will vary with numbers and types of connections
Here is the cheapest at $54http://www.newegg.com/Product/Product.aspx?Item=N82E16813135407