Everything Phatch and Foodpump said.
If you don't have a four-way "spaghetti" set with a large strainer, a steamer basket and a heavy (probably glass) lid -- you should. You will use this pot every time you cook pasta, for two layer steaming, for cooking a lot of chili, etc. Buying something more versatile argues for buying decent quality.
Foodpump hit the nail on the head when talking about a sandwich bottom. There are plenty of "good quality" choices below the All-Clad/Tri-Ply level. You don't have to spend top dollar for a good quality pot -- and you certainly don't need multiple layers all the way up the pot walls. One is a good number, even if it's the loneliest number you'll ever do.
FWIW, kitchens that make a LOT of stock FREQUENTLY, typically use inexpensive aluminum; because it's light, and cheap to replace when (even heavy) pots inevitably ding. ( That's not advice, Novice, it's just a general knowledge fill-in.) While I think an aluminum saute pan has its place in a budget-conscious home kitchen, too light a stock pot is a false economy. I have two myself. One is a good, 10 qt "four way" with a sandwich bottom, and the other a big old 4 gal, inexpensive stainless.