If using them, you'd probably have to have an average shipping charge that was a little win some, lose some to hopefully work out even in the end - I kinda do this just with using My Post, since their charges to rural areas are only discounted by a maximum of 5%, but at the same discount tier it's 19% for metro and 35% for same (major) city. (That in itself ticks me off sometimes. I often have to pay more to another close location in SA that Aus Post consider rural, than I do to a metro Perth area - I know it's a logistics thing but it still grates a little, since I get a high rate of rural (or what Aus Post considers as such) area orders that require upgrades to parcels, it's salved a little when I only have to pay $6 or so for a local order, at least, since I tend to waver between band 3 and 4 as most stuff goes by letter).