Excellent list but the barrier to entry is getting even lower for sharpening systems with 3M's new lapping films. This bundle is $14.99 and you get .3, 1, 3, 5, 12, 30 and 40 micron sizes. Just need some float glass or something similarly flat and you are off and running! I've heard these can last up to 6 months or longer with the same level of use diamond plates would see, the key to making them last is only pulling so you don't tear the film. Plus you are getting much finer than even extremely high grit water stones, for instance 16000 grit is ~0.9 micron.