Even if you don't go that often, for a 3 day trip, it is about $60 more than the other tickets. The free parking would save you $18, so you are only paying $40 more. If you use that to get the discounts on the purchases for your entire group or can plan another trip in less than a year, you save money. Basically if you spend $200 on food, souveniers, etc, you will be breaking even or saving money.
Last year, they were running the passes for $150 for a time and then after that it was $170 for 2 years (buy one, get one free). I would wait until closer to your trip dates to see what kind of sale is offered, but it is definitely worth looking into!