How to make a egg for robux?

Hello! I tried to make an egg for my coin simulator, which can be buyed for robux, but i don’t really know how to make it. Can someone help me?

Here’s the code i using for buying eggs:

RemoteEvents.Eclicked.OnServerEvent:Connect(function(Player,Egg)
	local EggData = Eggs[Egg]
	if Player.leaderstats.Coins.Value >= EggData["Cost"] then
		local TotalPets = totalPets(Player)
		if TotalPets < Player.PlayerStats.MaxStorage.Value then
			if EggData["Type"] == "Coins" then
				Player.leaderstats.Coins.Value = Player.leaderstats.Coins.Value - EggData["Cost"]
				UnBoxPet(Player, Egg, 0)
				RemoteEvents.ChangePetsValue:FireClient(Player, "TotalPets")
			elseif EggData["Type"] == "Robux" then
				
			else
				Player.leaderstats.Gems.Value = Player.leaderstats.Gems.Value - EggData["Cost"]
				UnBoxPet(Player, Egg, 0)
				RemoteEvents.ChangePetsValue:FireClient(Player, "TotalPets")
			end
			
		end
	end
end)

You use developer products, once they purchased, use MarketplaceService.

For example:

game:GetService("MarketplaceService").ProcessReceipt = function(info)
    if info.ProductId == 'yourdevproductidhere' then
        --do rest as they bought, make sure to confirm they have got everything by saying:
        return Enum.ProductPurchaseDecision.PurchaseGranted
    end
end)