how to use various shipping costs?

For postage I need to specify a cost relating to a product rather than an overall order.

ie: a t-shirt will cost £4.50 but a boxed cushion will cost £9.50 to post

We don't want to do this using the weight option.

We also want to offer an additional option for guaranteed delivery or courier.

How can we do this, I've looked on the postage add ons but nothing seems suitable

Any ideas???

What shipping method do you want to use for the guaranteed delivery or courier?

guaranteed would be Royal Mail and courier would be a local UK company

Is there anything to distinguish the T-Shirts and Boxed Cushions from other products?

examples: master_categories_id, unique weights, manufacturers, model number etc.

If there was something to identify these products then you could calculate the $4.50 and $9.50 per product for shipping vs the weight quote ...