I will of course respect the privacy of the seller concerned - but this is something of the communication I received after making a purchase of a French cookbook on Amazon.com.
The seller emailed me to say the cost of shipping the book was extra (more than double, in fact) than the amount set by Amazon, and said "Please let me know if you are willing to assume this cost, otherwise I'm afraid I must cancel the order."
Now - Amazon has this to say about shipping costs from Marketplace sellers.
Marketplace Shipping Rates
Your shipping fees when buying items at Amazon Marketplace are fixed according to the type of product you purchase.
How Our Rates Are Calculated
Amazon.com charges Marketplace buyers a flat rate for shipping, and funds are passed to the seller to offset the costs of packaging and labor, as well as the actual postage required.
The credit given to a seller will usually closely match what the seller pays to ship the item, using the option that you have chosen (Standard or Expedited). However, there may be times when the credit a seller is given for a Marketplace order will be above and beyond what is actually paid for postage. Shipping costs are an inherent feature in any mail-order service, and we hope that you will understand.
I was frankly taken aback by the seller's communication. I've NEVER received any communication like that from any other Amazon Marketplace Seller.