I've never even considered buying something off Silk Road. It'd be a good place to sell if you were a dealer, I imagine. But who can't find drugs just on the street? I guess it'd be good for non-American countries.
It's still risky unless you're an experienced seller and you know the ins and outs of securely transporting drugs/illegal materials via Fedex. Drugs are plentiful in many foreign countries, especially when it comes to opiates. I see where you're coming from though.