I've written about Lindt 90% cocoa chocolate before. I try to take some with me on every trip (along with macadamia nuts and beef jerky). Like I wrote earlier, his dark chocolate is surprisingly smooth for a high-cocoa chocolate, and a 40g serving has just 3g of sugar (by comparison, a 40g serving of a Special Dark Hershey bar has 20g of sugar).
It's usually $30 for a 12-pack, but Amazon has a lightning deal right now for $22.19, and the deal is already 53% claimed. I just bought some!