EVGA has launched an upgrade program for owners of its 680i boards that allows them to upgrade to a 780i board for a fee, no matter how old their board is. However, there seems to be a caveat, as owners of the "122-CK-NF68-RX WILL NOT be eligible for this promotion as this was sold as a recertified product."
You will end up with a 132-CK-NF78-XX board if you decide to take EVGA up on this offer and depending on where you live it will either set you back US$89.99 or €79.99, *UPDATE. You also get a three-way SLI bride in the box and free ground shipping is also part of the deal.
And yes, you have to return your current 680i board to EVGA and you have to pay the postage for this. The promotion is running for 60 days, but you might want to sign up as soon as possible if you own one of EVGA's boards.
You can find out more here, although you have to register or be a registered member already.
Update: According to EVGA Europe the European price includes VAT in Germany 19 percent, Austria 20 percent. European upgrade price in Germany would be USD 89,99 (net) = € 62 plus 19% VAT = € 74 plus shipping from the US = € 80 while Americans pay the Tax after they buy a product, depending on the part of the U.S, you live in. Now the price looks almost identical, if not identical.