I'm still mystified...

totally agree grannyring. I had assumed, maybe wrongly, that the outrage was for sellers who did not offer payment options other than paypal, but had the 3% fee as a mandatory add on...

I once paid for a power cord, and received an email that it would not be shipped until I sent the additional $2.65 paypal fee that I had forgotten to include...

@grannyring 

+1

I never let it bother me, I just go with the flow of the other person's situation. no point. Life has enough other hassles that are far more important and/or difficult to negotiate. No need to add to the pile. :)

Not every time is PayPal fee added just because you have another option. This is the first ad that I randomly opened.

https://www.audiogon.com/listings/lis953gj-accuphase-a-60-amplifiers-pair-solid-state

I assume that "shipping cost determined after the purchase" could be figured out before the purchase, once someone is a truly interested buyer. For this particular ad, I would think that shipping would be a little more than just a few dollars.