Newegg has the Ryzen 1700X for $149 which is the cheapest I've ever seen it, even used.
https://www.newegg.com/Product/Product.aspx?Item=N82E16819113429&ignorebbr=1
https://www.newegg.com/Product/Product.aspx?Item=N82E16819113429&ignorebbr=1