How do i create a ShopGUI Stock?

This is the code i have right now, the code doesnt work if i click on an item, and i just dont know whats wrong with it

local A = 0
local button = script.Parent

       local player = game.Players.LocalPlayer
local leaderboard = player:WaitForChild("leaderstats")
local button = script.Parent
local price = button:WaitForChild("Price")
local item = button:WaitForChild("ItemName")
local rs = game:GetService("ReplicatedStorage")

button.MouseButton1Click:Connect(function()
    if a == 1 then
return
end
 else
	 if leaderboard.Coins.Value>=price.Value then
        leaderboard.Coins.Value = leaderboard
        Coins.Value - price.Value
        local item = rs:WaitForChild(item.Value)
	
        item:Clone().Parent = player.StarterGear
        item:Clone().Parent = player.Backpack
A = 1
    end
end)

while wait()do
    button.Text = item.Value.."-"..price.Value
end 
    end
end)