Shipping cost all depends on the size of the order and where the thongs are going to.
Shipping is FREE for orders over $350.00 of spend on thongs.
For orders under $350.00, postage is at the expense of the customer.
Postage cost are fully viewable at the time of ordering as they are auto-calculated at the checkout page. Also, the amount of $$$ spend required to get free shipping is also automatically calculated and you can see how many more $$$ you need to spend to get free shipping, however, you have obviously missed seeing this, sorry.
If using a discount code this may bring the total cost below $350.00, if this is the case please add more pairs to your order as free shipping is only for order over $350.00.