For you sons you want to look at a Shred Stixx Skywalker for off-shelf boards. These may be out of stock, right now.
Otherwise, a number of companies can make them a custom fitted board, but these will be more expensive than the Skywalker in general.
A custom board will run you from $600 to $800. There are not a lot of model boards that are sized for youth. An inland flyboy is a possibility but kinda pricey, and still a bit big for your sons. Also, I think it is out of stock.
It is my understanding the Red Rocket is completely out of stock, and no more will be produced in 2013.
Consider a Shred Stixx Big Chief, Airstream/Piranha, or Headband, as alternatives.
You can PM me and I am happy to talk to you about setting up your family with a couple custom boards that they will all love and progress on.