basically any Ryzen rig (Ryzen 1600 series CPUs seems to have the best deal). Video cards are up in price right now from the bitcoin fiasco but a Radeon rx 580 or GTX 1050 would be your best bet and probably G.Skill Ripjaw series for your ram (16gb or higher). your MoBo can be anything that runs AM4 socket. I run the Asus Prime b350 plus ($100) but there's probably something better for about the same price out there.
Ryzen doesn't support onboard graphics so a Video Card is a requirement for a ryzen rig.