I had been looking for a 7" display to use with my Beaglebone Black spectrum analyser for a while. The recommended 800x480 resolution LCD7 is still unobtanium. Searching ebay I saw many 7" LCD kits (ie uncased) with HDMI/VGA/2 composite inputs running off 12V, so I ordered one for $50.
It took just 10 days from ordering for it to get here. It was VERY well packed in bubble wrap. Powered up fine and displayed VGA from this laptop, composite video from the RPI and HDMI from the BBB with no issues. Just need to find it a case to protect it
This display system doesnt have the high resolution needed for some projects but will work fine as a portable monitor. For a higher resolution small display for the RPI/BBB I have signed up for the kickstarter project hdmipi-affordable-9-high-def-screen-for-the-rpi