My 13 year old son shoots the Darton Ranger II. He's starting his 3rd year of archery. The modules allows you to step the draw length from 17" - 28" with a range of draw weights from 15 lbs to 45lbs. Well built and will grow with him until he's ready for a full size bow.
http://www.dartonarchery.com/rangerII.htm
Good luck on your bow hunt.