I consider myself a competent straight razor shaver, but much less than that with a hone. A few months ago I purchased a Norton 4K/8K hone and struggled just getting a usable edge. I have since obtained a usable edge but it is only "usable". My professionally honed edge is superior. It seems obvious that the next step in the evolution of my learning curve is to move into a finer grit stone. I am looking to invest in that stone but the options are not only spendy, but confusing. So here is the question:

What is the best bang for my buck in regards to my next purchase towards my quest for the perfect edge?