We may be talking in circles a bit here? Maybe talking about domestic/int'l is tripping us up, when what I think we really mean is shipping USPS vs FedEx.

My basic point is that I don't ship bikes/frames via USPS, domestic or int'l, because I can't find 108" boxes, and it takes extra time to cut down the boxes I can find to meet their minimum 108" dimension. And that 108" size makes it more difficult to pack larger frames/bikes. So instead I ship via FedEx/bikeflights, since I seldom have to cut down boxes for them.

But FedEx is a lot more expensive than USPS to ship bikes/frames internationally, and since I don't ship bikes/frames via USPS, I don't ship bikes/frames internationally unless we're talking high-value items. Few buyers will want to pay $250 to ship a frame that cost them under $500. If they don't want to pay $250 to ship a frame that will cost them $2k+, I'm happy not to sell to them.

So, you are correct, it takes no more time to ship int'l if you're shipping via USPS, since you have to cut down a box to 108" regardless of destination. And I am also correct, it is more time-consuming to ship USPS both domestic and int'l compared to FedEx, my shipper of choice, because you have to cut a box down to 108" for USPS.

My usual shipping conditions large items are: "Shipping is $xx via bikeflights, tracked and insured, signature required. No int'l shipping on bikes/frames/wheels." Anybody puts up a fuss about that, doesn't get to bid/buy. Smaller than wheels/rims gets shipped USPS Priority, tracked/insured, both domestic and int'l.

My advice to bianchigirl, stated less succinctly, was meant to be:
Your potential buyer in Germany wants you to ship via USPS i/o FedEx because it's cheaper, but shipping via USPS will take more time/effort than shipping via FedEx because you will have to cut your box down to meet their 108" minimum. In addition, your potential buyer in Germany is even trying to specify what size box you should be using, to minimize his shipping costs.

I think you should think about whether spending the extra time/effort to ship via USPS to satisfy this potential buyer is really worth it to you. Is this an item you can't sell in the US where shipping via FedEx is more competitive with USPS, so you can spend less time packing? Is it worth pricing the item a little cheaper for sale in the US, again saving packing time?

And, he/she sounds to me like a fairly fussy/demanding customer. I have not found much benefit trying to satisfy fussy/demanding customers. I'd steer clear of this one.

Hope I kicked this dead horse enough...