prices take a dive friday after 5!!!
I love it, my parents live in MD and I try to go whenever I'm home. You might find coupons online, but I think it's worth the full price admission. I went when they'd just opened up the Australia exhibit, and the birds and different herps run around at your feet and stuff, it's pretty awesome. If you can, while you're up in the rainforest enclosure, find a worker/volunteer. Ask them where some of the animals are that are difficult to see. I forget exactly what is up there, but i know we saw a few frogs and other critters people don't usually see because they're tough to find. The workers try to find these animals when they get there to show to people and they seem to love to help.
Either way enjoy it and post some pictures up when you're done!!