While not all of us can have all of the cookware we want, many of us can have some of it. Which pieces you invest in has a lot to do with the type of cooking you do.
For instance, do you love to braise? If so, you definitely want to spend on a braising pan, since hot spots can really ruin your work. A braising pan with a heating core that extends up the sides for even cooking is worth the money.
If you sauté every night, a pan with excellent conductivity is essential, because rapid temperature adjustments are so important in this type of cooking. While aluminum is a great conductor, it's not a high-quality metal. But a stainless steel pan with an aluminum core gives you the benefits of a tough exterior along with superior heat conduction. Stainless steel with a coat of copper on the underside is also a great way to go.
You can feel secure spending here.
For sauces, both temperature control and non-reactivity are fairly essential -- and if you cook a lot of sauces, chances are you're pretty into your food. So upgrade here. The stainless steel with a copper bottom or aluminum core will do you well.
And then there are the times when, for you, the splurge may not really be worth it …