Looks like the 3 Baseball Dolls are from Twins Enterprises. If uncracked and unchipped, they are worth about $25 a piece. The Six Flags Doll is older and much cooler, in my opinion. I do not know the value, but would guess at least $100 if it's in clean condition.
Could be worth more, if it's a rare one. I personally have never seen one offered. A good resource would be John Bray of Nodder exchange...
http://nodderexchange.auctionhosting.com/
As a side note... I'm wondering if Six Flags will be forced to change their name in the near future?