The knife sharpening kit that I made is capable of making a knife sharp enough to shave with, utilizes easily obtainable parts, and never goes bad or develops "bowl"-ing problems. Some quick repair/maintenance and the knife sharpening kit is as good as new, with minimal costs.
Step 1: Materials
Container of Acetone ~ $10?
Spray Adhesive - $10
A variety of high grit sandpaper - $3/(pack of 5 sheets) * 5 packs = $15
cotton cloths (or cut up an old t-shirt) - Free
rubber bumpers (optional) - $3
smooth bathroom tiles - $0.80/tile *5 = $4
The high grit sandpaper can be found at automotive stores, or in the automotive section at Walmart. For those that done know, the higher the grit number, the finer sanding. You'll want 800, 1000, and 2000 grit sand paper at least. 200-400 grit sand paper would be used for a really dull, dinged up, and damaged knife that you want to remove nicks from. Though at 200 grit, you may as well use a dremel with grinding bit. While 2000 grit sand paper will give you a knife that you can shave hairs off with, if you are sharpening a straight razor and actually plan to shave with your blade, you may need to order higher grit sandpaper (4000 grit).
You'll want as large (long) of these sand paper sheets that you can find, and then get the smoothest bathroom tiles that you can find, that will fit these sheets of sandpaper. The sandpaper sheets that I found were 3.5" x 9" and the tiles I found were 4" x 8".
Everything else on the list can be found at a Lowes/Home Depot. The cotton cloths can be found in the painting section there.