->  TW> about $800 and the 850 Watt unit is about $1000
->  TW> That price includes batteries for 10 Minutes at full load.
->  TW> But still those inverters are NOT rated for 24 Hour Duty.

-> what would it take to build an inverter for that rating? is it just a
"simple"
-> matter of heat disipation or somthing else?

 It is a combination of Component Quality. the ones typicaly use the
lowest quality components avaialble. And Heat sink capabilities for
dispating the heat of the switching transistors. Since the units ara
Only designed for 10 minutes at fulkl load the heat disipation
capabilities wwere shortchenged in the design process. 
If you have web access you can search for Solar Power Sites and check
out their Inverter systems. They are designed for 24/7 duty.
And for the big boys you can even get 110/220 and 3 phase systems from
some of those suppliers.
--- Platinum Xpress/Win/WINServer v3.0pr5