Kids.woot! has the Kristal Education Space Age Ant Habitat for $10 + $5 shipping = $15 shipped. Goes for $30+ elsewhere. Based on a Space Shuttle experiment, ants live in a nutrient gel. LED lights in the base can be powered by USB or by 3x AG13 button batteries (not included). Recommended for ages 7+.
Kristal Educational Space Age Crystal Growing Kit for $15 shipped