500Mhz ARM (faster is better),
512Mb RAM (1GB would be better),
SD/Micro SD card 4G or greater (a second slot would be nice so one for software, one for data),
Video/USB keyboard/mouse are optional but could be used for development. Once installed, the system will be remote, accessed by ethernet (TCP/IP).
Client would like to keep the cost below $50 US in quantity (i.e. 250-1000).