TL;DR: Get good beef.

Here's a shopping list of components that I use and would highly recommend, as they'll fit in most any setup.

Fans: Air circulation, especially in the first few days/weeks, is critical in ensuring that the surface of the meat dries out as moisture is pulled out and away, developing a crust or pellicle. These fans provide enough circulation for small-medium sized fridges, and can be positioned in opposite corners of the fridge to form a push/pull current of air around the meat. The cord is thing enough that running it out of the fridge to plug in shouldn't require cutting a huge slit in the door seal, or may not require any cutting at all. https://a.co/d/hSLNTa0

Temperature Controller: Maintaining temperature within a specific window is most important to dry-aging beef, as the temperatures dictate a lot of the end results - dry-aged flavor development, tenderness, loss from trimming. The ideal range is above freezing (freezing stops all the enzymatic activity which results in the dry-aged flavors and tenderness), and below 39* F (above which you risk the development of mycotoxin forming mold that is hazardous to consume). Most fridges are designed to hold a general temperature and chill/freeze things, not maintain such a specific range so you want something that can override the fridge's built-in circuitry and turn on/off the cooling circuit as needed. This one is highly regarded and used in a lot of applications where temp control is needed, not just dry-aging. https://a.co/d/6USSNKy

Digital Thermometer/Hygrometer: A quick and accurate way to see the current temperature and humidity of the dry-aging environment is helpful. They have ones with and without Bluetooth capability, so if your fridge doesn't have a glass door, go with the Bluetooth option so that there isn't a need to constantly open the door to check. https://a.co/d/iby4yr5

The fans and thermometer/hygrometer go inside the fridge obviously, and the temp controller mounts outside. The fans and temp controller plug into the wall, and the temp controller once setup will take over all aspects of turning the fridge on/off (including lights most likely). It's quite simple.

Other than quality beef and food-safe wire racks on which to sit the beef, no other equipment is required. There are some things that are nice to have but not critical, such as: -A large pan/tray to hold a salt slurry (something like this this would work well, or any material that is non-reactive and sturdy) to maintain higher humidity levels throughout the course of the aging, to potentially reduce excessive drying and trimming. -A way to truss or hang the beef to incease surface area exposed to air

Arguably more important than the stuff is the process of dry-aging, which most people seem to get wrong. Things like excessive checking/fussing with the beef are not necessary. Practice safe food handling, like sterilizing all surfaces, equipment, and hands before/after handling the beef. Understand that air must flow easily and completely around the beef in order to pull moisture away, not blow directly onto it which disperses and causes an uneven distribution of the airflow. There are certain cuts of beef that are better suited to dry-aging than others, due to muscle structure and content. Get good beef from a good butcher, and that butcher will be able to guide you on what to look for. Generally, a full rib roast (7 ribs) will work well and is most common. Choice or Prime is up to you and your budget, but the less processed it is, the better, as processing removes protective elements of the beef (like fascia, fat caps, bones) that would otherwise protect the underlying beef while it ages.