Market Power and Prices in the US I'm trying to get a measure of market power in the US. Here's what I'd be interested in, ranked from best (what I'm really after) to worst (stuff that kind of hints at my measure, but isn't really it. 


Price distributions of similar goods in the US, by county/state
Average markups for different goods, by county/state
Average [other characteristic that correlates with higher firm market power], by county/state


Importantly, I'm after price distributions of goods consumed in state A, not produced in state A.

I guess I could use the Nielson data set to get some proxy of price distributions, but I don't think that's the strength of the data set. What else is there?
A paper just out of the oven provides a very comprehensive analysis of market power in the US for more than 50 years, using mark-up data from three different sources. The key graphs below: