You are talking about the 2x 27 grizzly combo grinder right? Because they make a 2x72 grizzly combo sander/buffer/grinding wheel as Damon linked to Amazon above. The 2x27 is $165 and the 2x72 is $584 plus shipping. If I may suggest a machine?
Get the Kalamazoo 2x48 sander which is rated five stars on Amazon and is my next purchase when I finish a set of kitchen knives for a pretty penny. It is $448 plus 42.65 shipping. I am feeling like a kid on Christmas morning at the thought of getting the Kalamazoo. We had them where I used to work same size and I have no complaints. You may have to build a bigger grinding work table for it as it is an industrial American made machine and the table it has is only about 2x4 if my memory serves me right. If you free hand grind your knives then it's no problem. It tilts flat and has a 5" contact wheel. The 2x48 belts are available in just about any configuration you want and are fairly inexpensive to boot. We had one at work that they had mounted to a table and they built a big 12" work table and mounted it to the table in front of it.