Limiting the number of 'golden' award for completion could potentially discourage people from sharing what they have found out so far, which I see as a good thing. Maybe even add more direct incentives with lines like "I wouldn't blab this information around if I were you. Someone might just beat you to the prize!".
well, not limiting the actual prize, but change it up so the "answer on the web" won't be correct for more than say.... an hour
Lets say that Roland Demise have about 1000 golden hammer of awesomesauce available. The quest starts with an innkeeper but you have to use the word " Hey, got any news on a new item?" (keyword news, new item in that order) and the innkeeper will reply
"Yea, but I wouldn't pass this around, but I heard that Roland know something about it make sure you say 'Sake' and I send ya" Of course at this time, Roland can hand out 1000 quest to the first 1000 people who can complete it and get the reward but if anyone else come by Roland would deny anything about the reward and send them to another NPC or back to a different innkeeper
Of course it would be cool if the message between the player and Roland are in private chat (whisper or whatever) so the public doesn't see what is going on
The game will have like 20 NPC the players can go to but only get 1 reward. After it cycle all 20, Roland will have it again and can go like, "I just got a new shipment of this stuff, would you be interested of doing X thing for me for it?"