You should be able to get several tens of thousands of miles out of the whole bike, except consumables (chain, tires, tubes, brake pads, bar tape). Wheels generally go out of true and spokes fail because the wheelset wasn't properly stress relieved and retensioned when they were built. It has little to do with how "cheap" the wheels are. Have your wheels professionally finished (or learn to do it yourself) before things start to go wrong and you will never need to mess with them again.