If you are an attachment junkie, then with your KitchenAid, the sky's the limit. From pasta makers and ice cream makers, to shredders and juicers -- they can do everything. Take care of your stand mixer and it will take care of you for life.
A real chef's knife
Price: $100 and up
The knife is the most personal tool in the kitchen. Think of it as a pair of shoes. It has to fit well to the contours of your hands and, when made well and taken care of, can last a very long time. There is no cutting corners here, you have to go out and hold a bunch of knives, simulate cutting, and then you will find your mate.
There are two main schools of knives: Western and Eastern. Westerns tend to come from Germany, i.e., Wusthof and Zwilling J.A. Henckels, though there now some beautiful American knife-makers. The Eastern variety is pretty much Japan. Both schools work just fine, so it ultimately comes down to comfort level and personal preference.
Once you understand a bit about the different qualities of metal and methods of forging, you’ll appreciate the value of your investment. A good starter Western is the Wusthof Ikon, and for Japanese, try the Misono. Remember, treat your knife with respect: keep it dry, sharp, and clean and NEVER, EVER put it in the dishwasher.