Hello 'glassnut',
<< we bid and won an item shipping cost was there so we paid now seller tells us shipping cost is twice what was listed in auction making item too expensive.>>
Did the seller contritely ask if you were wanting to cancel as a result of the discrepancy or did he seem to be using this as a ruse to get a separate payment?
Sometimes a new seller makes an honest mistake and does not know how to get the shipping sorted out. You still do not need to pay more, but you would not want to harm him either. If, however, he is doing it to get buyers to use the paypal Send Money in the anticipation that if he ever has to make a refund, the system will not force him to cough up the second little 'extra', -- well now that's different.
Something to think about come feedback time.
You cannot force him to ship, however, so if you refuse the extra he may cancel and refund and you won't get the item. Again, how you feel in feedback may depend on if he was honestly not very good at learning how to ship, or if he is savvy and trying to squirrel a little 'safety stash' on the side.
His choice is to ship or refund. You are not required to pay one cent more than what was in the listing.
Either way, if you do not get a refund or your item, you will have 30 days after the last estimated delivery date to file a claim through ebay:
http://pages.ebay.ca/help/buy/item-not-received.html#timeframes
