While probably not the least expensive one out there (~$22 USD), it definitely works and comes with the correct tip for the Karma. #263-1696 is a selectable voltage adapter (3,5,6,6.5,7,7.5V regulated). The box is labeled 'Digital Camera Power Adapter' and is clearly labeled 'up to 2000mA'.

The adapter comes with three power tips, the socket is clearly marked 'Tip'. The connector has +/- markings molded in, and the smallest one fits the Karma perfectly.

For the record. Link here.

-Zeke