You aren't going to get rich off of it. Most cable parks in themselves are not huge money makers from what I have been told. It is the Pro Shop attached to it where you will make your money.
Think about it, If you charge $35.00 for the day which not many people would pay for just a sesitec system because who wants to pay $35.00 to wait in line?
It would take you 10,000 customers to get to the start level of $350,000 throw in Insurance and cost to settle lawsuits which you will have (every cable does)
I just don't think it is a money making idea. Just my .02 though.