Do you actually have the shifters in your possession yet? They should come with cables if you bought them new. Ribble will only save you 2 or 3 dollars in this case. I've bought from that eBay seller before because once you factor in shipping there is barely a difference in price and you'll likely get the cables quicker.

The difference between older Campy cables and ultrashift has to do with the outer diameter of the shift housing. It is now slightly smaller to fit into new shifters. When people say that Campy 10 and 11 are not compatible, they quite literally mean that one uses 10 cogs and the other 11, so anything to do with the change from 10 cogs to 11 is going to be affected (The ratcheting mechanism in the shifter, the derailleurs themselves to an extent, the cassette, and the chain). Other than that it's all good.