It's hard for me to say if agency pricing has specifically effected my purchases since I rarely bought ebooks to begin with. Up until about a year ago I had no knowledge of who this "Big 6" were. Didn't know much of anything publishing-related issues, really. I just never paid any attention while I was buying up my small handful of mass-markets like the oblivious shopper I was.
Fast forward to now, I'm slowly (
very slowly) phasing out my support of the Big 6. I'll never be completely rid of them because there are a couple of authors whose ebooks I would absolutely love to buy, and while price isn't an issue with
those, DRM is. I estimate the total to be around $250-ish.