well the price vary alot, depends what you want to use, like if i use normal nmea receiver and map king the navigation cost is around rm400
if i use sirf garmin with map will cost around rm600, so very hard to price. some need obd II scanner, some don't need.
but anyway, the software and console is standard, so ... i try to get as cheap as possible.

the best is not to modify the existing electrical circuit, just use plug in cigarette and do not and never connect your inverter to battery, even it is fused. .

TIPS for customiser:
CAUTION for rotary users, please install voltage stabilizer and regulator; encourage everyone else to do so.
DO NOT USE IGNITION START SYSTEM as power ON method, (UNLESS U HAVE A DELAY POWER UP CIRCUIT FOR UR DEVICE)
this will damage your alternator + batter + maybe starter.
All factory car like BMW doesn't run on PC, they run on customize board; so they did enormous power drop calculation,
know how to stabilize voltage, properly fused their gadget and  .. etc 
my fren car battery die and alternator damage because of this ... so lesson learnt, never never do that .

easiest is to install on/off button, let ur car start up, let voltage stabilize, then turn on ur gadget.

happy experiment. waiting for slim casing.
update soon.

no update on this MOD?

if there's anybody else who might doing this, pls share with us the progress. TS very long time not online, make me wonder how his carpc right now.