We released our butterflies yesterday...it was a beautiful day. One immediately flew out but the other 2 had to be coaxed out (one was accidentally released a few days ago thanks to our wonderful toddler). It was an awesome activity, one I highly recommend. Our butterfly kit came from Amazon Insect Lore Live Butterfly Garden but I suppose you could get it anywhere. We did have to send in for the caterpillars separately with a little card (obviously they don't come in the box).
What an amazing way to learn about how things change!