The bench grinder market can be divided into three major types. The first group is the standard grinder used for everything from rough grinding to basic sharpening procedures. Usually it comes with two grinding wheels of different grid. One grinding wheel for the rough and the other for the finer grinding work.
These basic bench grinder range anywhere between some dollars up to $300 and more for really heavy duty ones. A good example of a very reliable heavy duty machine is the Jet bench grinder. 
Durable and powerful enough to handle most tasks in today’s professional environment.
Bench Grinders for Sharpening
The second group of grinders would be the specialty machines. Mostly standard machines but equipped with additional guides and jigs for precision sharpening. These bench grinders usually come with special grinding wheels which can sharpen up to HSS or sometimes even TCT steels. These specialty grinders are very common in many woodworking shops.
An excellent example is Delta’s sharpening center bench grinder. Equipped with a special 120 grit aluminum oxide dry wheel and a 1000 grit wet wheel, it allows to grind the blades dry and wet. While dry grinding gets the rough marks out of the blades, the fine water cooled wet wheel finishes the sharpening process without ever burning the top edge. In addition, a special sliding tool holder guarantees a fine straight grinding.
Waterstone Grinders With Leather Honing Discs
The last group is the low speed grinding or honing machine. Usually they come with a water tank which lets the grinding stone be kept permanently wet. This prevents any overheating of the sharpened blade. In addition, most of these 90 to 110 rpm low speed specialty bench sharpeners are equipped with an additional honing disc. The Tormek waterstone bench grinder is a very good example of this type of specialty sharpening machine. More about the tormek in our special article about this bench grinder.