eBay with Newegg and Newegg have the Lenovo IdeaCentre 5 AMD Ryzen 7 4700G Octa-Core Desktop Tower (90Q30008US) on sale for $640 with free shipping.

AMD Ryzen 7 4700G 3.60GHz 8-Cores, 16GB DDR4, 1TB HDD+256GB PCIe SSD

Integrated AMD Radeon Graphics, 802.11ac (2x2), BT 5.0, DVD-RW, Win 10 Home 64