There are already numerous threads about this (which you can see if you just go to page 2). To add to what SimplySimon said above, here is a quote of mine from another post:

Quote Originally Posted by Tom Millson View Post
It's a good idea but it's really easy to work out optimum price anyway. It just depends on your priorities:

Maximum possession for money
Just keep going up $1 a day until you don't get 5% bonus possession. Then go down $1 to get the 5% possession back. Keep like this until you feel it could go up.

Maximum money from attendance
Calculate ticket price (a) multiplied by attendance (b) to get the maximum ticket sales revenue (c):

a * b = c

Keep increasing ticket price by $1 as c increases until c starts going down, then reduce it by $1.