I got caught up in a similar situation. I ordered an item "as seen on tv" on line. They offered 1 free item if I ordered 2. The first 2 totaled $9.99. With postage ...I ended up paying $24+. The postage am't didn't show til after I'd clicked "pay". I didn't bother trying to cancel the order but I learned my lesson!
To add insult to it, I later saw the same item priced cheaper at our local Walgreen's.