>Gunpowder is not fundamentally harder to make than methamphetamine.
I think it's actually considerably easier. If you have saltpeter, sulfur, and charcoal, there isn't even any chemistry involved, and the only one of those ingredients that is remotely plausible (and I'm stretching the term "remotely plausible" here) to regulate the sale of is saltpeter. And even if they went that far, Wikipedia mentions an old process[1] for synthesizing saltpeter using only wood ash, urine, and straw. And your setup isn't even likely to explode or leak poisonous gas into your home in the process.
I think it's actually considerably easier. If you have saltpeter, sulfur, and charcoal, there isn't even any chemistry involved, and the only one of those ingredients that is remotely plausible (and I'm stretching the term "remotely plausible" here) to regulate the sale of is saltpeter. And even if they went that far, Wikipedia mentions an old process[1] for synthesizing saltpeter using only wood ash, urine, and straw. And your setup isn't even likely to explode or leak poisonous gas into your home in the process.
[1] http://en.wikipedia.org/wiki/Potassium_nitrate#From_urine