spending $200 on a sharpening stone - why you could get a good climbing rope for that price!
I wanted to experiment with very high grit abrasives for sharpening, but needed an economical approach: I used contact cement to secure 150 and 400 sand paper to some pieces of marble and glass.
Results were mixed, more experimentation is needed. This is apparently an approach used by carpenters to achieve scary sharp plane blades.