This is a good price for this. You of course need a KitchenAid stand mixer to use it but it will work with any of them.
I have it and I love the dicing blade. You have to put a bowl under it to catch the ingredients as they are sliced or diced or shredded. I really like that I can have this in my cabinet instead of a regular food processor sitting on my counter.
The downside is that the "machine" part cannot go in the dishwasher. But all of the rest can go in the top rack.
The cheapest I have seen it before was $93: