When I was selling a fair volume of kits on ebay, I quickly ran out of recycled boxes and had to start buying them. My pricing calculations were based on a figure of 75p for packing, not that I always felt I could get away with charging it. That was the total for the box, the tape,
some of the packing material (much was recycled), clear sticky-back paperwork pockets (so the delivery didn't depend on my awful handwriting) and printing out the delivery note.
Packing is/was whatever I've got and whatever seems appropriate. Bubble wrap, foam peanuts and 'pillows' (like giant, individual bubble-wrap bubbles) are nice but have a significant price if you have to buy them new. Shredded paper is generally free (junk mail
) but can get surprisingly heavy if you're not careful. If there's a lot of space in the box, toilet-roll tubes are a good way to fill it for not much weight penalty, since they're pretty rigid but hollow.
Royal Mail always used to charge purely by weight, which was favourable for kits, but then a few years ago they introduced size categories as well, and the combination of size+weight can
sometimes be very unhelpful for kits. I only realised after I'd bought them that those Airfix 1/48th Merlins were pretty much impossible to post for any price that a buyer would actually pay, which is why I ended up hauling them around to shows so doggedly.
One of the perennially frustrating things on Ebay is that many buyers perceive a 'fair' p&p charge to be related to the cost of the item, not what it actually costs to pack it and post it. For instance, if you sold someone a gold chain for £100, they'd think nothing of paying £10 p&p for it, even if all you were actually doing was putting it in an envelope and sending it recorded post with a 1st class stamp on it. On the other hand, if you sold someone a cubic metre of wet mud for 99p, they'd go through the roof if you asked them for £10 p&p, despite the fact that it's obviously huge and heavy...
