How could I make a shop usable?

So I have been making a shop for my game, and when you press the buy button, it gives you the item, but when you press the button on a different item, it doesn't give you the item, but still charges you for the item. I think it's that the game saves the variable and when you buy a different item, it gives you the first one. Also, this game's inventory is only supposed to have one item at a time, so the item gets replaced instead of added to the inventory. Here's the code:

BuyButton Script:

local img = script.Parent.ItemImage
local cost = script.Parent.ToolCost
local name = script.Parent.ToolName
local desc = script.Parent.Description
local buy = script.Parent.Buy

local replicatedStorage = game:GetService("ReplicatedStorage")
local tools = replicatedStorage:WaitForChild("Tools")
local buyTool = replicatedStorage:WaitForChild("BuyTool")

local mainShop = script.Parent:WaitForChild("MainShop")
local template = mainShop:WaitForChild("Template")

function GetChildrenAlphabetical(instance)
    local children = instance:GetChildren()
    table.sort(children, function(c1, c2)
        return c1.Name:lower() < c2.Name:lower()
    end)
    return children
end

--

local tool = GetChildrenAlphabetical(tools)

for index, tool in pairs(tool) do
    if tool:IsA("Tool") then
        local toolElement = template:Clone()
        toolElement.Parent = mainShop
        toolElement.Name = tool.Name
        if tool.TextureId ~= "" then
            toolElement.Image = tool.TextureId
        end
        toolElement.Visible = true

        img.Visible = false
        cost.Visible = false
        name.Visible = false
        desc.Visible = false
        buy.Visible = false

        toolElement.MouseButton1Click:Connect(function()
            img.Image = toolElement.Image
            name.Text = tool.name.Value
            desc.Text = tool.Desc.Value
            if tool.Cost.Value == 0 then
                cost.Text = "Free"
            else
                cost.Text = "$" .. tool.Cost.Value              
            end
            img.Visible = true
            cost.Visible = true
            name.Visible = true
            desc.Visible = true
            buy.Visible = true

            buy.MouseButton1Click:Connect(function()
                local buyTool = replicatedStorage:WaitForChild("BuyTool")
                local result = buyTool:InvokeServer(tool, tool.Cost)

                print(result)
            end)
        end)
    end
end

GiveItem Script:

game.ReplicatedStorage.BuyTool.OnServerInvoke = function(player, item, cost)
    if game.ReplicatedStorage.Tools:FindFirstChild(item.Name) and item:FindFirstChild("Cost") then
        if player.leaderstats.blinds.Value >= item.Cost.Value then
            local tool = game.ReplicatedStorage.Tools[item.Name]:Clone()
            player.Backpack:ClearAllChildren()
            player.StarterGear:ClearAllChildren()
            tool.Parent = player.Backpack

            local starterTool = tool:Clone()
            starterTool.Parent = player.StarterGear

            player.leaderstats.blinds.Value = player.leaderstats.blinds.Value - cost.Value

            return "BoughtItem"
        else
            return "NotEnoughCash"
        end
    else
        return "NoItemOrNoCostValue"
    end
end

If someone could give me an answer, that would be great. Thanks!