Hey, all. Jeremy from COMC - I think everyone here knows me. So when we were setting up the 'restocking credit' sale for BF weekend we were faced with an interesting problem: Someone could buy a card in simplified shipping mode so that the seller got their $0.25 credit, then they could re-sell it to the original seller for the same price and the reseller would also get a $0.25 credit. Rinse, repeat. It wouldn't be too hard for anyone unscrupulous to abuse the offer like that. Our choices were to either exempt all flippers from the special, which we didn't want to do, or adjust the way shipping fees were applied to cards flipped during the promo.
As you know we went with the shipping adjustment. The way it worked mechanically in our computers was like this: Anything bought druing the special by a buyer in simplified shipping mode has it's "is shipping paid for this card?" switch flipped - it's listed for $.25 more than the seller's asking price. However, an additional $0.25 is paid out (by COMC - the restocking credit). If the buyer decides to resell that card, though, the system checks to see if the card was bought through the special. If so, the computer tacks on a one-time additional $.25 in shipping to the list price of the card. This mathmatically prevents system abuse if the buyer of the resold card is in advanced reselling mode.
Someone elsewhere on the forums said it best: the stuff we do can definitely be a little overcomplicated, but if you break down the math it makes sense and we try hard not to pass any of that confusion on to the average site user.