I suggest to stay with standard Foam Mattress, Because spring mattresses get uncomfortable and springs can break. Broken springs can destroy your back. So therefore, avoid those spring mattresses and save money. Foam mattresses are longer-lasting and can save money.
Two foam mattresses are enough to fit a modern bed of today's designs.
I can give you my experience of the Five-star foam, which was un-opened for years. It stayed in my rot-iron bed for almost 3 years, but that was the terrible mistake we done, the springs were broken. Al though we didn't cared about it, until my aunt (whom is a doctor) suggested us to throw it, it can seriously destroy your back.