For anyone who doesn't have a Six Flags season pass this is a pretty good deal. I don't plan on visiting any of the Six Flags parks this year, but I figured I would pass it along: http://www.sixflags.com/stLouis/tickets/index.aspx (Note it says $59.99 but when you enter your Zip code it should display the $49.99 option if you are outside of the St. Louis Market)

That's what I've been getting for the past few years. Really good deal.

see you can get the play pass for a lot less and you get all six flags parks, i do not understand the difference

I see people talking about this "Play Pass" but every link goes to a Season Pass.  And this does get you in to all the parks (See Number 9 http://www.sixflags.com/stLouis/tickets/seasonpass.aspx).  Never heard of a Season Pass that doesn't.  You can buy a season pass for any park and it is good at all the others.  SFStL historically has the lowest though because it is a smaller market and has lower median incomes.  Based on all the sites I have looked at $49.99 is the cheapest you can get a "Play Pass" or Season Pass.  If you can provide a link that shows otherwise please share.