The beauty of the maker movement is that it's possible to build devices that are tailored precisely to your requirements, or that cost significantly less than an off-the-shelf alternative - or both. Imgur user TheShortWalk proved this recently with an impressive Arduino-powered external monitor for his digital SLR camera. Using an Arduino Pro Mini and an array of infra-red LEDs as a remote control for the camera, the monitor's body is assembled from laser-cut plastic with foam-padded grips while the buttons for its controls are 3D printed. The full image gallery does a great job of showing the various stages of the project, from the initial rough sketch to a cardboard form prototype and a highly-detailed 3D CAD model. The monitor can run from any 8-18V power source, and includes a rechargeable 11v lithium-polymer battery capable of running the device for over five hours - and cleverly held in place with elastic. A video overview gives a glimpse of the device in action, demonstrating how much easier it is to focus than with the camera's tiny on-body display.
I built an external DSLR camera monitor with a laser cutter, 3D printer, and Arduino Pro-Mini. It has 1280x800 pixel resolution, 5.5 hour battery life, and a built in IR remote to trigger photo and video capture on compatible Canon cameras.