Before you bid or buy from a seller that is using the GSP you can ask them if they will ship to you directly. But other than that, the only way to avoid those fees is to buy from sellers not using that system. In some cases, especially with heavier and/or more expensive items, it works out to be less expensive with GSP as their shipping rates may be better.
Even if a seller has an alternative shipping method listing, the buyer can't see it. Ebay has said they are looking into changing that so we may have a choice in the future but no guarantee.