There are many ultra-compact form-factor PCs Intel-based PCs around, but when it comes to AMD-based UCFF systems, the choice is somewhat limited, so pricing is usually inflated. Minisforum, which specializes in inexpensive ultra-compact PCs, recently started to sell its UM250/UM300-series UCFF computers, which pack an AMD Ryzen processor, starting at $299.
Minisforum's UM250/UM300-series PCs come in an aluminum chassis that measures 128x127x46 mm (according to Notebookcheck.net), which is just slightly larger than Intel's NUCs but still fits in the palm of your hand.
The tiny system can be powered by either AMD's Ryzen 5 Pro 2500U (4C/8T, 2.0GHz – 3.60GHz, 6MB cache, Radeon Vega 8 GPU, 15W, 14LPP) or AMD's Ryzen 3 3300U (4C/4T, 2.10GHz – 3.50GHz, 6MB cache, Radeon Vega 6 GPU, 15W, 12LP) APU. These aren't AMD's latest processors, but they are more than good enough for productivity and basic entertainment tasks. However, you should keep in mind that AMD's Radeon Vega GPUs have rather outdated media processing capabilities.
The UM250/UM300 can also pack up to 32GB of DDR4 memory using two SO-DIMM slots, an M.2 SATA SSD, and a 2.5-inch SATA SSD or HDD.
As for connectivity, the systems feature an Intel AX200 Wi-Fi 6 and Bluetooth 5.1 adapter, two GbE ports (which will be particularly handy for corporate users), four USB 3.1 Gen 1 connectors, one USB Type-C port that can be used to connect a monitor or any other device, two additional display outputs (DisplayPort 1.2, HDMI 2.0), and a 3.5-mm audio jack.
Minisforum's UM250 barebones with the Ryzen 5 Pro 2500U can be purchased directly from the company for $299. Meanwhile, a UM250 machine with 16GB of memory and a 512GB SSD is priced at $499 at Amazon.