There is no house advantage on odds bets.
The payoff on odds is based on the true odds. It's the best bet in a casino.
From The Wizard of Odds:
Taking the Odds
"Have you ever wanted a bet with no house edge? Craps offers just such a bet, as long as you bet on the pass line first. Once a point has been thrown you may bet up to some multiple, usually 2 times, your pass line bet on the 'odds.' The odds are simply an additional wager that the point will be rolled before a 7. Because the probability of the point being rolled first is less than 50% you win more than you bet if it happens. Specifically if the point is a 6 or 8 the odds pay 6-5, if the point is a 5 or 9 the odds pay 3-2, and if the point is a 4 or 10 the odds pay 2-1."
Of course you have to make a pass line bet in order to bet the odds. The link below has a chart showing the house advantage base on a pass line bet and the odds.
http://www.wizardofodds.com/craps