Spyderco Sharpmaker gets my vote for inexpensive, quick, light touch-ups. It is my most often used sharpener, since I try to keep my edges close to sharp and not let them get too trashed. Less than a minute on the SM restores edges nicely. But reprofiling an edge with this is tedious, to say the least.
Note: I do not have the diamond rods for this, only the two grits of ceramic triangular rods. Nonetheless, it remains my most recommended sharpener to folks who are just starting out, since it is pretty much idiot-proof, as noted above. Which is good for me.
Edge-Pro Apex (cheaper model) with the stone upgrade works okay for rather precise angle control and repeatability. It's okay for reprofiling an edge, but the coarse stone wears away rather quickly, compared to oil stones. For serious reprofiling though, my choice is now motorized belt grinders, hands down the most efficient way to re-form an edge. Edge-Pro is basically water stones mounted on slabs of aluminum. I like it enough that I bought a spare when one came up on the secondary market. If you get it from Ben Dale (president of Edge-Pro), you'll be dealing with one of the very best customer service guys I've ever found online. He is very forthcoming with info and very patient in answering questions about his product.
Another alternative is the Warthog V-Sharp spring-loaded sliding diamond rod system from South Africa. It offers multiple grits of rods and three sharpening angles - 17°, 20° and 25° - that sharpen the blade on both sides simultaneously. I've seen it locally at gun/knife shows for about $80.
If you have more time than money, learning to hand-sharpen on oilstones can be a fairly cheap way to go.
If you're willing to spend serious cash and are searching for the ultimate polished edge, Japanese waterstones work well for a manual system. I have a mix of brands, including King and Norton brand man-made stones, as well as some brands I don't know since I can't read the Japanese kanji on the stones. If I could afford them, I'd go with Shapton stones. For fantasy-land, there are the multi-thousand-dollar-per-stone extraordinarily rare natural stones from specific quarries in Japan. But those top-end stones, like some exotic cars, are sold only to cognoscenti whom the stone makers already know by reputation. You don't just walk in off the street and get one on demand.
Bottom Line: Spyderco Sharpmaker for touch-ups. Stones (your choice of Edge-Pro, oil, or water) for intermediate reworking. Belt grinders for serious hogging off of metal.
(edit to add) Here's a stone holding jig for either oil or water stones you already have laying around. It's sort of a "poor man's Sharpmaker" that is pretty easily fabricated out of scraps of wood, especially if you know a woodworker with either a table saw or miter saw.
I'll bet most have the Spyderco's I don't have any of them I don't care for them much the stroke just seems wierd to me for sharpening. Good luck.
