Gear investement
 

If I wanted to referee HS soccer this spring, what kind of equipment would I need to purchase?

You have whistles, lanyards, and undershirts/undershorts.
You would need the shorts, socks, and turf shoes, plus whatever jerseys are worn in your local area.
Additionally, there are cards and a notepad, pens, and a flipping coin.
Other than that you can use your basketball bag and whatever misc items that you bring to a bball game.

In your position, you could do it for about $200. Don't be cheap on your socks and shoes! Your knees and feet will pay a price if you are.