Browning Micro Midas III bows are fantastic. Relatively cheap, but not cheaply made. Plus they have lots of draw length adjustment and weight adjustment. My son has had one for 3 yrs now, he had a limb issue and Browning replaced them, all we had to do was pay the S&H. His new limbs give him even more poundage. He'll be able to hunt with this bow. Your son could shoot a bow like this until he's at least 12. I've pasted a link for you too. Hope this helps and good luck with your purchase.
Let us know what you decide.
http://www.browning-archery.com/prod.php?k=62106&u=0314