Buying Restaurant-Quality Cookware
I have a grudge match going against some of my older baking sheets. They've warped, gotten scratched, and generally haven't held up particularly well. I'll admit, I bought them from stores like Target inexpensively and you do get what you pay for. But there is an alternative: the local restaurant supply store. (See also: Gourmet Kitchens on a Shoestring)
Restaurant-quality baking sheets (along with other cookware) is meant to be used repeatedly over the course of a day, be banged around as staff get meals on the table, and be relatively easy to replace if you need to. They're sturdier, often thicker than what you'll find at the supermarket, standardized in size and — provided you have a restaurant supply store nearby — fairly similar in cost. If not, you may have to go online and pay shipping, but even then, the cost can work out since they'll typically last longer.
The Big Difference
The biggest difference I've seen between what I find at restaurant supply stores and the more typical retailers for home cookware is size. I was looking at griddles one day and there simply aren't any small griddles available for restaurants. It's obvious why: If you're cooking in a restaurant, you're cooking for more than just one family and you need to be able to handle multiple orders at once.
There are some pieces of kitchenware that just aren't practical to buy at a restaurant supply store, especially if you have a small kitchen. I just can't make use of a 14" x 23" griddle (the smallest I saw) unless the whole extended family is in town — and it doesn't fit in my dishwasher.
You'll have to examine your own cooking needs to know what will really work in your kitchen and what will fit in your cabinets. But odds are good that there are at least a few options down at the restaurant supply store that will save you money and last longer than their supermarket counterparts. Knives, certain kinds of pans, and dinnerware have been among the best deals I've found.
You will find some smaller differences between restaurant-grade cookware and what you might buy elsewhere. For instance, baking sheets aren't non-stick. That's not really a problem — a quick spray of oil or some parchment paper or a silicone baking mat will all serve the same purpose — and, after all, not worrying about scratching the non-stick coating can be a relief. It can require changing your cooking routine at least a little bit, though, and it's important to be aware of that fact ahead of time.