Check out Steam (tomorrow probably) - existing ED buyers will be able to get DKS at a reduction through the system they have in place.
Alternatively, you can get FOV if you have ED already, and download the ED+FOV to DKS patch that we hope to release in the near future (we're still making it)
Is the same offer available for GamersGate? As that's where I purchased it from. And to be honest, I'd rather get DKS instead of the expansion as I have doubts as to whether this patch you speak of will actually be released. Too many developers, etc., have promised similar in the past and then never delivered.
