Joerg,
thanks for the insight about the GTA4.
and i didn't have to reread the over 600 posts as the answer lies in a post i saw (& referred from the beginning) namely Sebastian's production cost "forecast" (whatever it might be based upon)

do i conclude correctly that for less then 10'000 units, it would only be an upgrade to a N900?
seems unrealistic to have even fans here do that kind of upgrade.
until i switched to (desktop replacement) laptops i have always designed & assembled my PC myself
so far i have only had to replace a LCD on a N900, but honestly? i'll pass on doing a hardware upgrade, sorry.
i'm afraid unless you reach 10'000 units or adjust the prices above 390€ to include a case as well...