I got my son a Remington Model 7 Youth in .243 for his 12th birthday. He's taken three does with it over the last two hunting seasons. When he gets a little bigger, we'll get an adult stock for it.

I think Weatherby sells a youth model that is packaged with both youth and adult stocks.

Howa also makes a youth model, and you can pick one up for around $400 with a 3-9 scope already mounted. Here's the Howa: http://www.academy.com/index.php?page=content&target=products/outdoors/hunting/center_fire_rifles&start=10&selectedSKU=03 45-03404-0243