To my surprise; I learned that my own country had at least one forum where the acquisitions of chemicals were discussed. And if my country, of 5 million, has it, then most countries will. The forum you are looking for are pyro(technique) forums for the so called pyro(technique) enthusiasts. These people are usually non-political but they love to blow things up and/or create various light shows. They usually create very specific supplier lists for a majority of chemicals that can be used in an explosives device. Most of them operate in a “gray area” so they act as a perfect source for getting both supplier tips and “shipping tips”. Many of them order online (this works as very few of the compounds are illegal, just regulated) while others take road trips to f example Poland to get materials directly from small factories. These materials are then smuggled without problems to the country of destination. Many of these East-Block factories will sell most chemicals to you as long as you seem like a credible buyer (non-Muslim, non-extremist).