The ODROID C1 is a single board computer with a quad-core processor that runs Android and Linux. And like the Raspberry Pi 2, it only costs $35.
ODROID-C1 Review
ODROID C1 review - Android Authority
ODROID-N2 Review
Android for the Embedded System – ODROID
ODROID C1 review - Android Authority
downloading and installing unbuntu 15.04 to odroid xu4 and other versions or similar boards
ODROID-XU4 Single Board Computer with Quad Core 2GHz A15, 2GB RAM, USB 3.0, Gigabit : Electronics
Showdown: Pi 2 vs ODROID C1 vs HummingBoard vs MIPS CI20
Imagination MIPS Creator CI20 review (updated) - Android Authority