Tool isn't being added into backpack and starter gear?

For first, you need to use RemoteEvent to send the informations to server and server give items and others.

Create a RemoteEvent and put in ReplicatedStorage. Now create a Script and put on ServerScriptService and put this code:

local event = game:GetService("ReplicatedStorage"):WaitForChild("RemoteEvent") -- Your event location.
local ForgetMeNotTool = game.ReplicatedStorage:WaitForChild("Flashlight") -- Your tool

event.OnServerEvent:Connect(function(player,item) -- On fire get player
	local leaderstats = player:WaitForChild("leaderstats") -- Wait for leaderstats
	local price = game.ReplicatedStorage.Prices[item]:WaitForChild("Price") -- Get price / Put price location. for this create a folder named as Prices in replicated storage. put item name and on Click send the item
	if leaderstats.Money.Value >= price.Value then -- If have money for buy
		leaderstats.Money.Value = leaderstats.Money.Value - price.Value -- remove money
		--Give tool to player.
		ForgetMeNotTool:Clone().Parent = player.Backpack
		ForgetMeNotTool:Clone().Parent = player.StarterGear
	end
end)

Now. create a LocalScript in your button and put this script:

local event = game:GetService("ReplicatedStorage"):WaitForChild("RemoteEvent") -- Your event location.

local item_name = script.Parent.Name -- Put item name

script.Parent.MouseButton1Click:Connect(functoin()
	event:FireServer(item_name) -- On click fire the event and send the item for server.
end)

Remote Events are designed to provide a one way message between the server and clients. This message can be directed from one client to the server, from the server to a particular client, or from the server to all clients.

Wiki pages:

RemoteEvent/Function

Hope it helped :)

Errors? tell-me on comments.