Universal sells both a 1-day 1-park ticket and a 1-day 2-park ticket. If you want to go to both parks on one day, you need to buy the 1-day 2-park ticket. Obviously, it is the more expensive ticket. I think Universal is selling a 2-day ticket for slightly more than a 1-day ticket. If you can go on 2 days, this may be the cheaper option. And no, there are no super cheap 1-day tickets sold by anyone anywhere.