I sometimes list items on Ebay for friends who are less than computer literate. No matter what I am auctioning, if the shipping price is more than than the actual shipping price and more than $1 I send a refund back to the buyer.
I recently bought a new upper half to my Cory glass coffee maker on Ebay. The woman packed this thing so well it took me a good 30 minutes to to unpack it. Inside there was a very nice letter from the seller thanking me for my business.
That was so nice of her to do that.
Sometimes the postage isn't printed on the box, so you can't tell how much the seller paid in shipping. And I think a lot of people who get gouged on shipping didn't look at the shipping charge when bidding. I know in my early days on Ebay I got stung a few times like that.
I have found a good way to check the shipping is to check the shipping on similar items that other sellers are selling. Usually if they are overcharging it will stick out like a sore thumb.
And yes one time when I contacted a seller before bidding on an item about the shipping cost she said it was to cover: the fuel for the trip to the post office, the "wear and tear" on her car, compensation for the time she spent waiting in line at the post office and the cost of the box.
BTW, the new Priority Mail boxes have the words "Priority Mail" stamped on the reverse side so sellers can't reverse the box anymore. We have a nice shipping store near us with a very large selection of boxes. They aren't all that expensive.
But I add the cost of those into my shipping. I guarantee new boxes when shipping.
And I agree with running an auction for an item concurrently with Craigslist, Greensheet, etc. List it on Ebay and if it doesn't sell, THEN list elsewhere.