I sold plants on eBay for 3 years. I never charged more for shipping that it actually cost to ship the plant(s) for the first 2.5 years. I never got a negative feedback...I got one neutral in 3 years. But I got tired of doing it. It took me a while but I figured out why sellers try to make money on shipping....it takes so much time to harvest, box and pack, and actually mail all the stuff, that by the time you have done all that, AND used your gas to get to the post office, you have actually lost money just in time spent. And, residents of your state, who are supposed to be required to pay sales tax, will do almost ANYTHING to get out of it. I got tired paying their sales tax. And eBay fees and PayPal fees take a large bite out of your profit margin. I eventually went to a flat rate shipping charge for every sale. I didnlt overcharge, but I made certain I put in enough leeway to cover the cost of actually mailing the plant, and a handling charge for my time/materials (often, things just wouldn't fit in the FREE USPS boxes) and enough to cover FL sales tax that was likely to be ignored by FL buyers.
But I have been on the other side too. I recently bought some plants from someone on eBay who I have been buying from consistently for about 6 years and almost always had great experiences with. These particular plants were expensive because they are quite rare. When I received them, they were small (but I expected that)...and the box had been completely decimated by the USPS. It was crushed, one side was completely open...I was lucky the plants hadn't fallen out! The most rare and expensive plant was severely damaged.
The thing is, even with the severe damage to the BOX, the plant probably WOULDN'T have suffered the way it did if the seller had paid attention to packing! There was ONE measly piece of newspaper padding in the box with multiple plants! They were sleeved, but that was no help. They needed padding like popcorn or at the very least more paper wads or maybe paper shreds to fill in the collapsible space in the box. I documented all the damage and emailed the photos to her immediately and she is sending a new box of plants this week. So she's making good on it, but it should NEVER have happened...ESPECIALLY when she charged me over $10 to ship a box that cost her at the MOST $4.50 to ship.