Tickwt help

I want to go to both universal parks and harry potter what are the cheapest tickets I can buy to do all 3 things

I don’t think there is an inexpensive option. You can get park to park tickets which lets you into both parks (and is necessary for the Hogwarts express) and then choose yournumber of days. Check out the Undercover Tourist site for prices - they are a little bit cheaper than Universal directly.