I never charge more than the post office charges me . However some people complain that the shipping charges are to high and ebay penalized me because of it , limiting me to how many items I could list . Their solution to me when I complained to them was to offer free shipping . That works when you have a item like a chip you just add the shipping to the opening bid and state free shipping . That doesn't work for large items because of the big changes in mailing cost depending on where it goes to.
In your case the guy clearly is using shipping cost for added profit . I'd would not do business with him again.