$30?!
I can get them at the local shop for £5! But yeh, patience is needed, and
DO NOT do anything to disrupt their live. Add no weed, ad nothing after they've grown. They die. They're fragile. They will kill each other, kill their babies and even kill themselves given half the chance. Let your kids have involvement so they feel a part of it, but nothing unsupervised or they will most likely accidentally kill them. They're not easy and they are living things.
Here are some pictures of what you might end up with, what you're likely to end up with, and just a close picture.
Might
Probably Will
Close up
P.S - If possible, that thing that ferox said would be sweet! I'd love to see their progress. You could make a whole thread about it!