Ebay purchase and game theory, low stakes

[darwinbulldog]

I recently won an ebay auction for $2.91. I paid that plus $2.75 shipping. I received a delivery notice from USPS indicating that I owe $0.85 in postage, so I'm guessing that means if I don't pony up another 85 cents, the card will be returned to the seller (roughly 1,000 miles from me) who was somehow able to get it to my neighborhood with insufficient postage.

Clearly the card is worth more than 85 cents to me, and the seller knows that, so will he just count on me to make the short-term economically rational decision of paying the additional postage to get the card, or will he worry that I might refuse to pay out of spite and then demand a refund or a second mailing of the same card? (Clearly the USPS doesn't care, or they'd realize it's cheaper to just give me the card now that it's in town already, and realize that I'd realize this, and so on ad infinitum.) Or will he just give me the 85 cent refund? He seems inclined not to so far, but then, I haven't explicitly asked for one. What is the economic value of one negative feedback posting to someone who already has feedback in the thousands? So many mildly interesting questions, and all over 85 cents.