Flat rate shipping PER CATEGORY

Hi Zenners,

How do I enable Flat rate shipping say $19.95 for UNLIMITED ITEMS in the same CATEGORY? (or group of categories).

So if they order 1 phone or 2,3,4,5 unlimited phones it is still $19.95

If they order 1 camera or 2,3,4,5 unlimited cameras it is still $19.95

But 1 phone + 1 camera they pay $19.95 + $19.95 = $39.90 for example?

Think of it as we have 2-3 WAREHOUSES that we ship orders from
categories A,B,C are in warehouse 1
categories D,E,F are in warehouse 2
etc

So as long as customers order items from the same warehouse / group of categories we specify its flat rate shipping?

how do I do this, pls help!
cheers

You could write a function to determin how many categories are being used and then alter the flat rate as flat rate * number of categories ...