They are allowed to go, and there is a reduced price ($35 might be right, but don't quote me on that.) Keep in mind that this is not the regular safari, and not all kids want to be seated quietly in the safari vehicle for 45 minutes in the early morning when they are full of energy.
We've taken it twice, and the first time it was all but ruined by children who should not have been on it--they just weren't able to sit quietly and enjoy it, and they were melting down on the ride.
The second time there were also some toddlers, they were well behaved but towards the end were getting very antsy, I think had it lasted another five minutes they would have become disruptive. You know your chldren best, but if they tend to be energetic in the morning you might want to wait a couple of years before trying this one. It's a lot of money to spend if your children aren't going to be able to enjoy it.
Anne