special shipping config, is this possible

I have a customer who needs shipping prices to be figured by number of items purchased and what category the items are in. Is this possible?

For example:

A visitor purchased 1 item from Category A and the shipping is $2.50
but also purchased 1 item from Category B and the shipping for that one item is less at $1.50

Ive yet to see any shipping that is based on category but it is what we need unfortunately.

Any help or a direction to get started would be great. Ive done several mods to OSCommerce and understand its inner workings.

This could be designed but it would take quite a bit of work to put together the relationships between Products and Categories and the amount to charge based on quantity ...