It costs money for cardboard, tape (the, hopefully, sticky-on-one-side-stuff), wood, screws, strapping, clips and cushioning material, plus a lot of labor (we have had to spend days just protectively packaging and securing some of the more complex items) to double pack things to meet the shipping requirements USPS, so that your goods will, hopefully, arrive in undamaged condition. We currently ship mostly by FedEx Ground (for domestic USA shipments with shipping weight under 150 pounds and less than about 130 length + girth) which seems to be less damaging to things but we still try very hard to pack things in a manner that has a high probability of avoiding damage in shipping. Even in the case where USPS provides priority mail boxes, we still have to pay for expensive bubble-wrap and labor.
Buyers who come and pick things up from us directly don't generate these costs. Since we don't know in advance if a buyer is going to come pick it up or have it shipped, and since nearly every item is different, we have no way to build the cost of packing into the price on ebay. Furthermore, on the bigger items, some people elect motor freight with no packing because they are only after the parts while others want lots of packing to try to make sure there is no damage in transit (Motor freight carriers only insure used items at 10 cents per pound.) Furthermore, some buyers have asked to have things like jackhammers sent UPS without packing (FedEx charges an extra $5 special handling fee and there may still be some packing charge if the item has sharp edges/corners that must be covered to protect FedEx staff from injury).
(Additional insurance may be available on request and payment but is not quoted in our standard issue pricing. Ask in advance if insurance is an issue for you--you will not get it if you don't ask and pay for it.)
Our packing charges vary considerably, depending on the item and how much material/time it takes to get it packed. (These charges actually average much less than what the combination of materials and time cost us. We are not trying to make a profit on these but we also don't want these costs to put us out of business.) An item that is heavy and delicate (like optics) will take more packing than something that is light, small and indestructible. Packing charges for most small things run between $3 and $10. Bigger generally means more cost. Items on the larger end of what can go FedEx ground can easily cost $30 to $50 for protective packing. Really big and delicate items like large format plotters that can cost as much as $100 to pack. Things that need to go by truck carrier ( Less Than truck Load) usually cost $50 for a skid, strapping and wrapping with cardboard then stretch-wrap (typically required packing by LTL carriers for used goods like we ship). Once in a while, there is something that can makes since to go via moving van via blanket wrap service but this usually costs more. (LTL regulations don't allow things with wheels to be shipped on their wheels because they could roll around and damage other goods). Oversized (more than 48 by 40 inches) items that require a custom skid generally cost $100 for the skid, strap and wrap service. The best protection for items is crating but this typically cost $100 to $300 per crate--depending on size and complexity. Items that are already in shippable packing, may not, at our election, be charged a packing fee (often thinks that are in packing, still need additional over-packing for adequate shipping protection). A buyer can also request packing and shipping by a third party such as Mailboxes Etc. and we will be happy to only charge the buyer the actual cost of getting it to that third party and whatever their actual charges are but beware that this may cost you 3X or more what we would charge to pack it. Buyers should always be aware that packing for any given item could exceed the high bid price, particularly if it is something big/delicate or has a low minimum bid. We are doing our best to keep this charge as low as possible. However, if you have a concern about what it is likely to be, make sure you give us your shipping details and ask us to make an estimate prior to bidding.
Note that we use recycled packing materials whenever possible. While this general does not decrease the overall cost (it takes more time/labor to get recycled materials, handle them and use them, we feel it is the correct thing to do from an environmental perspective.
INTERNATIONAL shipment packing adds some additional issues. The big one is that any wood product must be heat treated and marked so as to prevent transport of any insects or disease. This costs more and generally precludes the use of recycled wood packing. If we are loading an ocean container for you, you will have to pay for the cost of chains, binders, straps, etc. that may be required to secure the load in the container (you do get to keep these items when your container arrives--one can never have too many chains and straps.