Some more cheap SBCs from my bookmarks: - BananaPi (Allwinner, MediaTek): http://www.banana-pi.org/ - Le Potato (Amlogic) and Renegate (Rockchip): https://libre.computer/ - NanoPi (Samsung, Allwinner) : http://www.friendlyarm.com/index.php?route=product/category&... - OLinuXino (open hardware, Allwinner A20, A64, etc, iMX, Ralink): https://www.olimex.com/Products/OLinuXino/ - Odroid (Amlogic, Samsung): http://www.har…
One example is the new WandPi 8M. It's based on the NXP i.MX8M and has a few key advantages (particularly, true gigabit Ethernet and USB 3.0). I've ordered one myself, but I'm not sure exactly when they're supposed to start shipping.
There's also the x86 based UP boards. They're based on newer Intel Atom SoCs, so my guess is that the out-of-the-box Linux support would be fairly decent.