You can find them here. Side note: apparently KORG has a parts shop on Reverb as well. Some other brands including Waldorf are also listed.
Update: the sale appears to have ended as of at least Aug 5.

"Sharing some big news: Today, KORG USA dropped thousands of KORG OpSix Synths on Reverb at a steep discount - nearly 60 percent off.
Fans of the brand will be able to buy brand new OpSixes directly from the KORG USA Reverb Shop. (One heads up - this is a US-only opportunity!).
For around $330, musicians can walk home with an incredible deal on a funky, fun synth just begging to be used for FM synthesis experiments. In fact, everyone from synth nerds, to bedroom producers, to guitarists and pedal heads would do well to take advantage of this deal: The OpSix’s Randomize Function -- which lets users to completely scramble the synth’s parameters, generating a new, unique sound -- is perfect for those looking to take their first steps into making some new sonic discoveries.
Check out the KORG USA Reverb Shop here [click here for the OpSix directly]. It’s definitely a great option for musicians looking to try something new at an affordable price!"