So, while discussing this with some people, I overlooked a trivial defense against linking prices to listings. A seller could list a legal item at the same price. If a buyer wants to evaluate a seller, he asks for the seller's identity key. With that, he knows how many transactions the seller was involved in, and the amount of BTC involved in each transaction. Let's say the seller has one item, a gram of cocaine at $98.50 (a unique price, which is dumb to begin with, but go with it). My idea with fuzzing prices was that the seller would accept random transactions between $88.50 and $108.50 (or some range), so the public price couldn't be linked to the listing. But if the seller simultaneously lists a legal item (or two or three) for $98.50, then there's no way to prove (within the requirements of the legal system) that the other $100K in previous transactions were cocaine. If the buyer is LE, all he could do is present a list of transactions at the same price, even though other products exist at the same price. He couldn't prove how many of each product were sold. I really need to bounce these ideas off kfm.