This is a recurring discussion here, and it fascinates me each time.
Is there really a difference between a seller saying:
1) Book costs $1030, but take a $30 discount if paying cash or check;
vs
2) Book costs $1000, but add $30 if paying via fee-based PayPal;
The only difference is mental, right? Why does the phrasing in #2 bother us so much more than #1? This is just a rhetorical question, of course...just one of the vagaries of human psychology, I suppose...fascinating.
It makes it seem that the vendor is being put out by a service that provides instant payment and security -- both of which clearly facilitate Internet transactions.
They might as well total up additional percentages for packing tape, boxes, bubble wrap, the cost of gas to the postal outlet, the mental stress of leaving the house ...