I guess it depend who you are. Although I scrape every extra nickel to buy a pin...there's no way I would go back on my word for more cash...on a sale
Case in point I offered up a pin for sale an put it pretty much everywhere. Well MrPinball must have had some issues because the add didn't post for 4-5 days. I made a deal with a pinsider for the sale of the game. Before the game was picked up or shipped, I had a full asking price offer ($250 more than I sold it for) from a relatively local guy that saw the add on MrPinball. Of course that would have also saved me packaging and palletting...leaving work to meet the shipping company...etc. There's no $ amount you can put on your word... or a 'handshake.'
On a side note I've never made a deal to buy a pin (CL included..and I've 'stolen' a few from CL) and got backed out on from the seller.
Maybe it's karma at work...