This is why I hate this ##!!ing Auction House - it doesn't solve any economic issue whatsoever.
Consider every suggestion presented here - they are all punitive to players (some more than others). Lower drop rates, items that expire, or flat out having to destroy items (salvage). This is outrageous to me.
Blizzard's solution is salvage, but think about little sense this makes. They expect players to have to salvage high-end legendaries and rares to craft the best items. Who is going to do that when those items have value (both to use and on the AH) when all they get in return is the chance to craft an equivalent item? No one, because it's stupid. That's not a realistic solution until those items become saturated, at which point players will start salvaging the surplus. What then? The market for those legendaries and rares will still be saturated while the market for these crafts will be fresh - but eventually those crafts will become saturated too. What then? Salvage isn't a solution for these items.