Pledge shipping is delivered almost exclusively via ocean freight to our backers, whereas at the moment our online store delivers our product to our customers via air freight.
This has a few implications, firstly, that ocean freight is generally cheaper than air freight.
If you're purchasing product through our early access store, you will receive the product we have in stock sooner but it will also cost more to get it to you. Next, because we are already shipping you a pledge, the cost to add an item to your shipment is generally lower as well.
In short, pledge add on shipping is cheaper because it's being delivered by ocean freight.