Some people buy name brand aspirin. Others buy generic, knowing it's the same thing and thinking of the first group as chumps. To them you can now say, "Chumps! I make my own."
Aspirin takes away pain, fever, and inflammation. Its active ingredient is known as Acetylsalicylic Acid, and each tablet has about 325 milligrams. It was first synthesized in the 1850s, but the process was time consuming enough that it was abandoned until the 1890s. The company that marketed it didn't want to put all their eggs in one basket, though, so they sold both aspirin and a much more effective pain-relieving drug; heroin. Although only heroin has been made illegal, many argue that aspirin wouldn't have made it through a modern FDA process – not because it's bad for people, but because so many people are allergic to it that either the trials would have been cancelled or no one would have bothered to market such a comparatively cheap painkiller.
But even if the FDA does decide to pull aspirin from the shelves, you don't have to go to a store to get more of this stuff. You may, however, have to take a trek into the woods. Early incarnations of the compound were made by boiling the bark of the white willow tree. That harvested the acid, but in a form that most people weren't interested in trying. The boiled potion was bitter enough, and caused severe enough stomach upsets, that they'd rather take the pain. Adding a little salt cut the bitterness, but it didn't help the stomach irritation.
It finally made it to the shelves some time after a man decided to do whatever it took to relieve his father's painful arthritis. To synthesize it without the bitterness, the scientist mixed its pure components, salicilyc acid and acetic anhydride together in a flask. The components couldn't be allowed to burn, so it had to be carefully heated it in a beaker of warm water. When the substance was finally warm, he added a few drops of water to it, and then it was practically done! Except for the purification. It had to be repeatedly crystallized and re-crystalized using jets of ice-cold water and alcohol, over a series of days. When it was finally done the gentleman gave it to his father; who we hope very much enjoyed it without the bitter taste. You, too, can do this process. All it takes are pure chemical components, precise temperature control, and days of rewashing the same beaker to get a fine crust of powder at the bottom.
Okay. Maybe it's better to just go to the store.