[Chrysalis]

A few points to think of here.

Retail stores always will charge more then needed simply because there is always someone there to pay it, usually when you see a sale belive it or not they are still making a profit on the item the normal prices tend to be very high markup.
If the vendor has a online presence and retail shops they always have different budgets and treated seperatly, to me this seems dumb since the money ends up in the same bank at the end of the day, but big businesses have been splitting of like this for years now.
With ebuyer I also agree there should be standard royal mail option in fact I prefer that, my doorbell doesnt work and when I order from there it is a nightmare as I often miss the deliveries and the courier they use is very poor and badly priced. As you said a royal mail delivery is better priced for buying small items. But saying that I think expensive delivery prices are deliberate the prices are marked up so they have a profit margin on the delivery.