How do I make a shop work on my clicker game?

I need help making the shop on a clicker game I’m working on, I need help on the shop tho, but I’ve managed to get the shop to pop up but I can’t figure out how to make the player able to buy items.

You need a variable with player’s money, a price variable for each item, and a button to buy and do the math (if money > price, set money = money - price).