Geeky birthday gift
As I age, I find myself buying gifts for myself that my younger self would find horribly disappointing.
For example: for my 2014 birthday, I spent $15 on a large sheet of plate glass (Woo-hoo!!!!). Plus a bit more for some sandpaper.
The above photo shows the glass on our back porch bench -- for scale. Shiny!
I believe that most people call this the "Scary Sharp" approach. The notion is that, when sharpening, you start at the coarse grits and work your way through all the successive grits.
The disadvantage of this approach, compared to using sharpening stones, is that you have to buy new materials more often: sandpaper doesn't retain its abrasiveness as long as a whetstone.
But, the advantage is that you always retain a perfectly flat surface -- whereas whetstones eventually get "dished" and you need to flatten them. This approach also provides more gradations in the level of abrasiveness.