Blizzard tried the whole real money for gold/stuff thing and it was a disaster in Diablo III. I definitively wouldn't take that route at all. All it did was turn the game into a full time job for people that were trying to get drops to sell for real cash.
Deterring the gold market seems like the correct solution, but it's probably not going to work. This is akin to the prostitution market. You can try to deter Johns, but there's still way too much demand and people will just work around it. Same goes for illegal drugs. There's still huge demand for it, and the actions taken haven't really done anything to stop it. You can't really control others actions or feelings. You can only control your actions.
Really, this is a software problem; more precisely, a spam detection problem. Email servers have these kinds of protections in place for spam emails to your inbox and most of them work fantastic. SpamThrottle is a great addon, but it's pretty rudimentary. It's still the best one we have right now, but until someone implements spam detection like yahoo's or google's, simple tools are the best bet.
