ABC News is reporting that Polonium-210 can be purchased over the internet:
Polonium-210, the radioactive substance that killed former Russian agent Alexander Litvinenko, is easily available on the Internet, but it could take $1 million to amass a lethal amount, according to leading authorities.
Polonium-210 isotopes are offered online by a number of companies, including United Nuclear of New Mexico. The company sells polonium-210 isotopes for about $69 but says it would take about 15,000 orders, for a total cost of over $1 million, to have a toxic amount.
United Nuclear today posted an online clarification to answer concerns they are selling weapons of assassination.