Maybe I'm in the minority but I pay close attention to shipping costs from sellers. I keep track of what they charge me, then look to see what the actual postage was on the outside of the box/bag/envelope when I receive my item. I'd say 75% of the time the numbers aren't even close to matching.

Now I know the boxes/bags/envelopes cost money (that is when a cheap-ass seller doesn't just reuse something that's already gone through the mail--my personal favorite) but (and I've gotten pricing for these items at the P.O./Office Depots/Office Maxs and other supply stores --yes I have no life) and the numbers don't  add up. Say I pay the seller $5.00 in shipping (based on a recent example) and see that postage was $2.75. Pricing for middle of the road envelopes (which, sad to say aren't usually used, low-end are) are $44.99 for 100 at OfficeMax. Add sales tax, make it $48.15-ish. Then divide by 100. That's 48 cents a piece. We'll even make it 50 cents just to help with the math. Occasionally, though not often, the seller will throw in a little extra cardboard to make the item a little less bendy. This is usually cut up boxes or junk from the gutter, definitely not high-end specialty stuff. But we'll say, just for the hell of it, another 25 cents, which is extremely generous. So, 50 and 25 and 2.75 = $3.50.

On the few occasions I've emailed a seller about why I was charged what I was charged for shipping they like to add in "the time it took to package and mail the item." You know what, not my problem. I don't get paid for the time I spend driving to work. I don't get paid for lunch. I don't paid for a lot of things related to my "job". I'm not paying the seller by the hour for an item. I'm paying for the item. So, I'm paying a $1.50 for your time? Or am I paying for you to offset your Ebay/Paypal charge?

Another of my favorite things, and a great way for me to never do business with a seller, is the Set Shipping Cost crap that some of them pull. Doesn't matter what you get, could be a postage stamp, hell, even an empty envelope of air, you'll still get charged the same ridiculous price. If you're buying a buttload of items from the seller then the set price can sometimes work, but it's not often that a seller has a lot of stuff at once I want to get. As soon as I see that set price thing, I'm looking for another seller.

Maybe I'm being petty (I don't believe so) but if you're going to make money on that, I'm not doing business with you.

Shipping costs should not be a way for a seller to increase their profit.