The Asus Tinker board, quad core ARM Cortex A17@1.8 GHz, 2 GB RAM, GBit Eth, 4xUSB 2.0, HDMI 2.0 up to 4K, WIFI b,g,n, Bluetooth, GPIO

ASUS Tinker Board is a Raspberry Pi 3 Alternative based on Rockchip RK3288 Processor

You can expect mainline kernel support and Debian 8,9 + Ubuntu + Android OS.
The price will be about Euro 65 with VAT.
Asus Part number: 90MB0QY1-M0EAY0 EAN: 4712900552874
https://www.proshop.dk/Mini-PC-Android-Raspberry-Pi/ASUS-Tinker-Board-2GB/2577743
https://www.proshop.de/Mini-PCs-Android-Raspberry-Pi/ASUS-Tinker-Board-2GB/2577743
https://www.jimms.fi/fi/Product/Show/126524/tinker-board-2gb/asus-tinker-board-harrastelijan-tietokonealusta-2gb

The board is designed to boot from an external micro SD card, like the Raspberry PI, this is a good idea for prototyping. The drawback is that SD cards are slower and less reliable than on-board eMMC chips.

Results from the work done for the MiQi board from mqmaker (mainline kernel 4.10) are usable on this board.
https://forum.mqmaker.com/t/mainline-kernel-compilation/572
https://github.com/Miouyouyou/MyyQi
https://github.com/rockchip-linux