UnitedNuclear has these and a bunch of other interesting tidbits if anyone wants to give it a try. I bought a small bottle of heavy water as well, which I of course sampled and can confirm it has a slightly sweet taste to it.

You really have to get your eyes adjusted to the dark to see anything with the spinthariscope. It ends up looking mostly like static on a green crt, but if your only reference frame is a cloud chamber, the volume of particles that are emitted from such a weak source is pretty remarkable.