Correct. There is no option to pay and get you from 4 star to 5 star more quickly. You still have to grind no matter what. Ironite is pretty much good for Sands refills (you have to time them properly so you don't waste them before you level up since they don't stack with the free refill you get after leveling) and gold. Gold goes very quickly when upgrading talismans. VERY quickly.