There's an item I'd like to buy on eBay and on the auction page when I click the Shipping tab and enter my zip code it gives me three shipping prices. The first is $15.59, the second is $6.91 and the third is $28.80. How do I select the second method for $6.91? When I click "Buy It Now" it defaults to the $15.59 shipping method and adds that into the total price, then asks me to commit to buy it for that price. I see no option to change the shipping to the other, cheaper method. What do I do?