I'd recommend trying one of the science supply companies that Universities use. You can get a group of bullfrog, leopard, or wood frog eggs/tadpoles. They are easy to raise, because they are from a temperate region. All you would need is am aquarium, air stone, some live floating plants, dechlorinated water, place some live daphnia in the water. This will provide oxygen, food, and hiding places for the developing tadpoles. Then as they come along development, place rocks/branches that allow the later developed/proto-froglets a place to get out of the water (so they wont drown). I would go with wood frogs, because of their size and extreme hardiness.