Today, there are already several “computers on a stick” on the market - full-fledged computers, of a size not much larger than the usual flash drives. I will give here a brief overview of the available models.
Already sold
Intel Compute Stick

$ 134
www.amazon.com/Intel-Compute-Stick-Windows-BOXSTCK1A32WFCR/dp/B00W8T61O0Appeared in March 2015. To some extent became the legislator of standards. The processor is a quad-core Intel Atom Z3735F, 2GB RAM (1GB for the Linux version), and an 8 or 32GB eMMC drive. It is inserted into the TV or monitor into the HDMI connector, there is a USB 2.0 port, a slot for MicroSD and micro USB for power. Built-in Bluetooth 4.0 for connecting keyboard and mouse, 802.11bgn Wi-Fi for the Internet.
iView Cyber PC Compute Stick

$ 116
www.amazon.com/gp/product/B00U3UW136?tag=digitren08-20')
Almost the same stuffing as the previous computer: Intel Atom Z3735F, 2GB RAM, 32GB drive, pre-installed Windows 8.1. Differences: no fans (silent), no need to connect to power if the monitor supports HDMI MHL. Included is a wireless keyboard with a touchpad. The keyboard resembles a gamepad - there are all sorts of additional keys, incl. multimedia
Tronsmart Mk908II

$ 55.9
www.amazon.com/gp/product/B00EO0MKMI?tag=digitren08-20Unlike previous computers, this one is controlled by the Android operating system. Also, it does not stick directly into the HDMI port - a "mother" connector must be connected to the monitor with a cable. Processor: Cortex A9 quad core and Mali 400 GPU. Android 4.2 OS, Bluetooth 4.0 and 802.11b / g / n Wi-Fi connectivity. 2GB DDR3 + 8G NAND Flash.
It has an external rotatable antenna for Wi-Fi.
Lenovo Ideacentre Stick 300

£ 129.99
shop.lenovo.com/gb/en/desktops/ideacentre/stick-300Processor: Intel Atom Z3735F Processor, Windows 8.1 OS, RAM: 2.0GB, 32GB drive, and SD slot for memory expansion.
Not yet on sale
Archos Stick PC

(planned $ 99)
They promise that it will be the cheapest of similar computers - cheaper than Intel and Lenovo. The hardware should be similar, while the new Windows will already be preinstalled on the computer.
Asus chromebit

(up to $ 100 is planned)
Unlike all those mentioned, this computer will run ChromeOS. While the exact characteristics are unknown. Rockchip RK3288 quad-core with low power consumption claims to be the processor, memory will also be made 2GB, plus 16 GB drive. Positioned as a device for students.
Asus vivostick

(planned $ 129)
Another product from Asus - this time with a full OS. The computer connects to monitors and TVs via the HDMI connector. It has an Intel Cherry Trail processor. Typical 2 gigabytes of RAM and 32 Gb storage. Additionally, the device has 2 USB ports and an audio jack, as well as support for Bluetooth 4.0 and Wi-Fi. The computer is running Windows 10.