I've been using AccuSharp for about 20 years and it's the most important tool I own. In the garden I use my grandparents' tools, and part of keeping them going is making sure they are sharp. When hoes, pruners, shovels, trowels and other garden tools are sharp, they last longer and make the gardener's life easier. About twice a year I go over the working ends of the tools with AccuSharp and it makes life so much easier in the garden. I bought mine for around $10 and they can still be found for about the same price locally.
I've got one for garden tools and another for kitchen knives, although for a long time I used one for both jobs. (Just don't tell my wife!)
You'll never regret having one of these around and when ever I speak, I always bring it along to show the difference between a dull tool and a sharp one.