What makes a great designer kitchen is rather like what you go on to prepare in a recipe. The ingredients are subjective and will vary depending on personal taste but they will usually fall into the following catagories:
Under each of the headings write down what ingredients you desire.
Start with the appliances, they are generic items and easy to research.
In the same way as cars are available at different price points so are appliances. Brand loyalty and identity sometimes inform decision making. It may be a good idea to have a wish list of items with prices for the same appliances from two different manufacturers at two different price points.
In this way you give your budget flexibility, a high and low point can be established.