I buy and sell on Ebay. If I run across an auction with a starting bid of 99 cents, knowing there is no way it could be that inexpensive, I check shipping charges. If I saw your auction with 40.00 in shipping I would know you were trying to make up the cost of your item in shipping fees. Ebay has rules against this practice.
I'm not saying 40.00 is out of line to ship a machine. I have shipped many and I know the costs. I can usually send one in new packing boxes and materials via UPS for 30 to 35 dollars for a full size vintage Singer.
If you want to get back what you have in an item price it that way in the auction, set your shipping to a realistic amount and you'll probably sell it.