I personally have had REALLY good experiences with rewarding my children for reading. They see reading as their job. Jobs earn money and their job earns points. I find that they work harder and push themselves more with a reward system.
If they are working to get something that they really want like a game for their Ipad they will sit and work sometimes for over an hour to try to gain that reward faster.
I put their points on a poster board and (they use their fingers for help) every night they hlep me add their points to the poster. So they actually learn addition/subtraction ideas at the same time. When they spend 20 points they subtract 20 and start from whatever number they have left.

My Reading/Learning reward system is as follows:
(3 points are possible per story)
3 points-perfect effort while reading
2 points good effort while reading
1 poor effort wil reading
20 points equals a prize worth about $1