Last vacation, we went twice. Once for a 1/2 day at BB after AK, and once a whole day at TL.
You don't have to spend that much money. If you're going to eat there, the prices are really similar to the fast food counters at the other parks...and typical grill type food. I'm not sure if you can bring food into the parks....
We spent money on the extras. DD got her hair wrapped--I think it was close to $60. (yikes!) DD and DS both wanted tatoos--this depends on the size of the tattoo--but I think average might be around $15 - $20. You can also get your picture taken everywhere and then stop at the photo stop as you leave and they'll print them up for you. These are great action pics and wonderful memories! We always try to get one with all of us on the family float ride...the big innertube. (Note--the family float ride at BB is WAAAAY better than the one at TL).
I never took a 2 year old there--so I really can't say. But when my kids were 5 and 7, and then last year when they were 7 & 9, they never get tired of this place and never want to leave.