Lenovo ThinkCentre M90n mini desktop PC with Intel 8th Generation i5-8265U CPU, 8GB memory, 512GB SSD, Wifi, Bluetooth, and Windows 10 Pro for $399 with free shipping. Normally sells for about $500.
It's small, at 7 x 3.5 x 0.87 inches in size.
Wireless mouse and keyboard are included. After adding one to the cart, click "View All" under "System Specs" to see wireless keyboard and mouse included.
The system specs are very good for the price, and has plenty of ports for components: four USB 3.1 ports, two USB-C ports, DisplayPort (for video), headphone port, and Gigabit Ethernet port. A PC with these ports and a i5-8265U CPU would normally sell for at least $450.
Could be a hot deal for someone looking for a very low-profile PC, and has a monitor to hook it up to.
The downsides: The 8GB memory is soldered to the motherboard, and cannot be upgraded later. That little memory is enough for common productivity software (Word, Powerpoint, Chrome browser, photo editing, media player, kid's computer, home theater PC, live streaming, etc.) but not enough for a graphic designer, video editor, or software engineer. Not meant for playing 3D games at high quality, although its Intel UHD 620 is surprisingly powerful for an integrated, on-chip GPU. Non-gaming graphics-intensive tasks work quite well, including multiple monitors at 1080p or a single monitor at 4K, watching HD videos, and doing basic photo/video editing. Platform (2D) games should also play fairly well, and some 3D games will play at low quality settings, but overall game-players will be disappointed. A modern iPad or iPhone will have better 3D quality, and for a home theater PC with gaming capabilities, an Xbox or Nvidia Shield TV Pro are more designed for games on a TV.