The RazorPit, which costs $20, seems a bit steep. In fact, a rubber door stop would probably serve the same purpose, but the effect is clear: I'm getting over 30 shaves with my Mach 3 razors (which cost close to two dollars for one blade). I dry off the blade with a towel, then wipe the blade across the RazorPit, moving flush. Then to get extra sharpness, I stroke the edges of the RazorPit, hitting the edge with the razor at a 45 degree angle.
Adding the latter method, my current Mach 3 has so far given me 30 shaves and shows no signs of dulling.
I should add that after sharpening the blade, I put my razor in a coffee mug of pure mineral oil (baby oil doesn't work as well, I found).
Overall, I'm saving hundreds of dollars per year in razor costs. The RazorPit and the mineral oil are good investments.