if you are going just for one day, buy them in advance on line.
if you print at home, make copies. cut the excess paper off around the ticket if you want.
this way if they get shredded in your pocket and the bar code is unreadable, you have an extra.
same for if you do the water rides and ruin the paper pass.
if you buy at the gate, it is ticket form not the print out paper
you will avoid the process of standing in line to get your tickets that morning when you reach the park.
it is not the money that i am thinking of but the time you waste in lines before you even get into the parks.