A kidney, but it's worth it.
It depends on dates and how many days but loosely, it would cost you $165 per adult & $160 per child for a park hopper (which you need it you want to go to both Harry Potter locations and ride the Hogwarts Express) so $650. Multi day tickets are cheaper as are tickets if you stay at a Universal resort
If you go to their website you may get cheap tickets depends on the month you want to go
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