This sort of highlights a problem I've been running into. I have a prototype of a device I'm looking to build running with a Raspberry Pi, but I would love to use a BeagleBone Black for the advanced chipset features and greater power efficiency. However, I can't find any low-cost small screens to use with the BeagleBone. With the RPi, as mentioned by samworm, you can get cheap rear-view camera screens and they work just fine. With the BBB, you either need HDMI (and big and bulky cables) or find a screen that somehow plugs into the GPIO ports. These don't exist.

For the record, cheap and small is <$50 and <4" (>2.5"). Never been able to find one. It's a shame the RPi is so terrible, technically speaking.