I am very happy to combine shipping for up to ten items for one postage charge. My site is set to combine postage costs automatically provided you checkout and pay for items together. I am afraid I cannot refund shipping costs if you do not wait, combine your purchases and pay for them together, as eBay charges me transaction fees on a per item basis which cannot refunded.
If you are buying several items, I am happy to wait for ups to a week for you to consolidate your purchases and pay for them together.