I love the look and functionality of a 8 inch or so screen displaying navigation and engine information. Advanced Flight systems has a setup like that listed for several thousand dollars, but then you have to upgrade it with sensors, etc. There are some others also, from Garmin down (price wise) So, how about taking a barebones computer (probably a laptop for light weight), stripping of all unnecessary brackets, case, etc., and basing a EFIS around that? Use a remote (add-on) screen, preferably a touchpanel, mounted on the panel, with the existing screen (in the case of the laptop) disconnected entirely. Remove the hard drive, boot from flash and run from RAM, saving all data to a (separate from the boot disk) flash card. Run the system off filtered alternator / battery power, with its own internal backup. Use a cheap USB or serial GPS system (even most cheap ones support WAAS now) – Garmin sells good ones under 100. A PIC or AVR microcontroller, again interfacing thru RS232 or UPS has enough channels to digitize data from engine sensors, a pressure transducer for altimeter, accelerometer for G-meter, etc Should be a XM-radio module that can get weather information. Add a cell phone interface to enable wireless Internet weather downloads etc. Decent graphics card would mean that adding a second screen is trivial Do you think that you'd end up saving money over a equivalent commercial system? I think it would. Might end up close to the cost of fairly cheap unit, but with significant features, not to mention ease of adding features as needed. One would have to put a lot of time into it, but aren't homebuilders already all right with that?