This is the basket in its current state. Straight chocolate bars are on the left; flavored bars are on the right.
I've picked up bars at regular and upscale supermarkets, Asian markets, and specialty stores. Cheap chocolate usually doesn't come dark enough and I avoid the most expensive bars, but this blog might be a good excuse to splurge.
If you haven't eaten a lot of dark chocolate, you'll probably find it somewhat bitter and lacking the creaminess of a nice milk chocolate (though dark milk chocolate does exist). I've found that what I'm used to strongly affects what I taste when I eat chocolate. If I've been eating a lot of 85%, 70% tastes overly sweet, as though the sugar overshadows the cacao. If I've been eating some sort of 65%, flavored bar, 90% tastes incredibly intense, like a full-bodied red wine. I suspect this will influence how I review the bars, which will be an interesting challenge. It also might influence what you think of the same bars--what's tasty to me might be unpalatable to you--but the experimenting sure is fun.