The first time we went was with the Resiterns, and they paid our way so it was free! We had so much fun (I think this was back in September--it was almost too hot still, but bearable). I took the kids because Erik had to work.
The second time we went was with a group from our ward. We paid $6 a person (group rate) but still better than $18! I was almost too cold this time (December 31st) and the animals didn't seem to have as much ambition for food as they did in our previous trip, but it was still fun. Erik got to go too!
There were a couple of downsides to this last visit to the park. The tour guide just had to tell us a horrible story about a newborn giraffe getting it's eyes pecked out and killed by some buzzards. I think the ride would have been much better without that tidbit of info (ignorance is bliss, right?!). Also Elisa stuck her hand in the cage of a peacock and got her little baby hand pecked at. It didn't do much damage, just scared her mostly. Stupid birds and their stupid pecking beaks.