I am 13 and I use a Barnett compound bow. it goes up tp a 27 inch draw length with a 45 pound draw weight. However, if you do i would get a whisker biscuit. I have one and it works awesome.

The first bow I bought my son was Browing's Micro Midas. That was a few years back and there are probably many more youth bows on the market now. I do like Mathews Genesis, it looks like a great first bow and the draw length will adjust untill a bigger bow is needed. At Age 8 I was cutting limbs and making my own bows. Even a 20-30 dollar pawn shop, low poundage long bow or recurve bow would be fun for an 8 yr old. I have several low pound recuves that I keep so my neices and nephews can shoot when they visit us. They always enjoy shooting when they're here.