just use "hakuzen" or "head-fi" words in the notes of the cable (together with your plugs choices) when making the order. use the coupons from the store, plus aliexpress coupon if you have it (for example, "friday10" to get $10 off during black friday), set "other payment" or "bank transfer" payment method, make the order, but don't pay it. the seller will adjust the total price, applying a 10% off over the total (except shipping costs). once adjusted, you can pay the order. you can also message them instead of adding the words in the item notes.