Ahhh... this seems so familiar...
Our guild (Outlaws) did a competition in the form of a race from one end of the DR .. pretty much to the other.
And it didn't turn out too bad... not as good as we'd hoped.. but not as bad as we feared it could!!
(We had approx. 17 racers)
My advice on this would be...
#1) Get another guild or two sponsoring/supporting the event, even just as referees... because they'll help get the word out to the players they already have an in-game relationship with and a few established guild's names will help add credibility.
#2) Many regular players won't budge unless there's either a strong RP element to it... or there's a prize of at least 100k... so maybe upping the prize to the 100k mark might have helped.
#3) Have prizes for 1st, 2nd and 3rd place (I think we did 100k, 50k, 25k) - then people will feel as if there's more of a chance of them actually getting a prize.
#4) In-game, in-character... have your guild ask people if they would like to win some trias... spread the news about the race... bug people if need be (but do it in-character, in-game and keep a note of who you've asked already so you don't bug the same people twice!!!) - Make a list of all who express interest so you can /tell them more once you've got a list of people who'd be interested.
But, the above is all just opinion ... just from the experience we had with our DR race.
