Those panels aren't cheap. Certainly they should either pay for it or return it. I agree the seller should "absorb"the cost too. By absorb I mean it should be built into the price or into shipping. I don't think it is unheard of to expect to pay for shiping. I mean how else am I supposed to ship it to you safely with the contents still alive? It is an expense that isn't free on my part just like feeding the snakes.
I agree if I sell 500 mealworms or 5k mealworms the 5k shipment doesn't become 10x more expensive. I can pay for shipping and still come out in the green quite easily. In reality every customer doesn't order $2500 in snake or $500 or $50 in mealworms. You can state "Anything over x price will include free shipping", but the smaller orders need to have all expenses worked into the price or shipping. Assuming we are talking about an actual business here. Not Joe Smith selling 2 clutches a year at $30 a pop.
Maybe I see it differently. I agree you don't need to tack on an extra "box fee". It is just that if you order a snake from someone they have to ship to you. That means having a box filled with all the necessary requirements and actually packing up said snake or feeder in my scenario. Time is money. Handling, box requirements, these things aren't free and should be built into the price is all I'm trying to get at.