Back in 2016, I created a study that compiled Michel catalog data and allowed you to compare the relative cost of collecting across various collecting areas. I created two versions, one for just German collecting areas listed in the Michel Deutschland Spezial catalog, and one with Worldwide data from Michel.
The thread discussing the previous Worldwide version of the study is
here.
I recently decided to update the studies with current catalog data. The German version is ready, and can be found
here. The Worldwide update is in the works, but I'm waiting on a shipment from Michel.
With the 2018 version, I've also added the ability to filter by date range, with the caveat that the date range must be entered first due to technical limitations which I haven't yet overcome. The date range leads to a few odd results, as the Michel source data uses a single date across a set rather than by individual stamp, and there are occasional typos in the dataset and/or odd entries that you never realized were there (like Deutsches Reich entries with 2006/2008 dates due to Michel listing a couple reprints).
Feel free to stop by a try it out.