Hmm. sounds like a lot of unnecessary tables...the reason why i say that is currently the 2 different shipping costs that are in use all work fine. I think I have explained myself wrong with what I want....
currently the 2 shipping costs I have is:
a) Main products = £7.00
b) Vouchers = 99p
(the only calculation I need at the moment is, if vouchers are purchased with main products then the 99p is deducted (so rather then both vouchers and main products being purchased together at £7.99 - the cost of shipping would be £7.00 (since voucher shipping is free with main products) this all works perfectly....
however lets say, next year delivery costs are increased...so the client needs to increase the £7.00 shipping cost to lets say...£7.50). at the moment the value of the shipping cost is hard coded in the eCart object...what I would like to do is rather then type the value of 7.00 in the eCart object, to simply put in a reference of the record from the products table in the eCart object) this way at any time the Admin can login and change the value of the shipping cost.
(I didnt mean to suggest that each product would have a shipping cost which would then be added together).
Have I explained my intentions in a better way :)