I2Som PanGu, an STM32MP1 powered Raspberry Pi Linux alternative that costs ~US$72.50
The 105.5 x 70 mm SBC is based on the STMicroelectronics STM32MP1, a dual-core MPU that integrates two ARM Cortex A7 cores, along with a Cortex M4 chip. I2Som has included 512 MB RAM too, which it complements with 4 GB of eMMC flash storage. You could expand upon this with a microSD card though, should 4 GB not be enough for your needs.
The PanGu also has several USB ports, HDMI, a parallel port and a MIPI DSI. Moreover, the board has a 3.5 mm stereo headphone jack, an 80-pin board-to-board connector and a 30-pin 2.0 mm pin with support for ADC, CAN, FMC, GPIO, I2C, SDIO, SPI, TIM, UART and USB. The PanGu has an Ethernet port too.
The board runs Debian Jesse and Yocto Linux, with Stephen Vicinanza of CNX Software stressing that it offers features that are "lighter, more robust and have the developer in mind with multilanguage capabilities" than other comparable SBCs. I2Som has a wiki for the board, although this is currently only available in Chinese. You can order the PanGu from Taobao for 499 RMB (~US$72.50).