Not to justifly the cost( I also think it is excesive)
but not all fabric is the same
in the last week I have shipped flannel,kona cotton, and batiks
In a large flat rate box I can get over 30 yds of batiks, only 20 if kona and only 10 of the flannel
I don't make money on the shipping and yes it is expensive!
and also the ebay listing with Free shipping usually have the high shipping charges built into the cost of the item
this is how they are getting around the ebay rules!