The phrase "postage charge" refers to the amount of money you have to pay to send a letter or package through the mail. It is the fee that covers the cost of delivering your item to the intended recipient. Full definition
Please remember to include the applicable postage charge when calculating the value of your order. (elaeisorganic.com)
Don't forget to factor in packaging costs when calculating postage charges — buyers often don't expect to pay much more than the price of postage itself, so you may wish to factor packaging costs into the price of the item. (moneysavingexpert.com)
This is such a shame, as I can not find one single online source where I can buy everything without having to go to so many different places and pay humongous multiple postage charges. (deliciouslyella.com)