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???