I will cut right to the chase here. I have had personally very little success bribing my children to stay in bed later, stay in their rooms, rest quietly during nap time. Professionally, I have seen very few families have solid success with incentive programs. I have heard of promised toys, promised treats, even promised vacations - trip to Disney World if you stay in your room until 7. I also have seen (and engaged in myself admittedly) empty threats, promised cancellations for play dates, loss of tv, loss of iPad, and so on.
That said, they could work. I can say so with confidence because it's working for me right now in my house! Granted my son is older and his incentives are about doing homework, piano practice, and being nice to his sister.
Here's my advice:
make your incentive small and immediate - if you stay in your room until 6am (for example) you can have a treat at breakfast, a special surprise ... pancakes with Hershey kisses? A new creature from a creature tube? A temporary tattoo?
do not threaten to take away anything in the heat of the moment because you probably will not be able to stick to it in the morning.
make sure that your prize isn't too hard to earn or too conceptual - sometimes a trip to the toy store doesn't make as much sense to your child as you think it might.
put some prizes in some sort of see through container that can visually motivate your child. Tell them they can pick a prize if they successfully complete their sleep challenge.
Finally - make your sleep challenge or goal realistic for your sleeper. If he wakes up every day at 5:30, make his goal to stay in his room until 5:45, then move it to 6 and so on. Or if you want to teach a rest time, start with 10 minutes a day and then go from there.
One last little nugget of advice. Make sure that the comforts of you and/or the entertainment that you offer in the early morning isn't too much of an incentive for your sleeper to wake early. If playing games, watching tv, or having yummy snacks is your go to plan to survive until a respectable hour, then you might want to make the early morning less fun.