Daniel
I don't know your price range but I'll give you a few suggestions.I hope it is ok to list sites, if not,forgive me.
Go to tradgang and look in their sponsor links under Git-R Done archery and you will see Check Mate recurves in the clearence section.They have some light ones for $200 also some other brands for $125-150.I can't say enough good about the Check Mates.They are adult bows in kid weights.The listed weight is at a 28 inch draw.You can take off or add about 2 1/2 pounds per inch for shorter or longer draws.
Black Rhino makes nice child and youth longbows from $65 for bows for 3-4 year olds to $220 for a legal hunting weight for a youth or woman with several models in between.
www.bows.net is their site.They are all made just like your new longbow, not a piece of fiberglass junk,
Quinn sells target recurves in about the same price range with limbs in a lot of weight ranges.You can take a look but I think the 3 pound aluminum risers might be a little heavy unless your oldest is big for his age.
Over on tradgang I know Doug that builds Turkey Creek longbows if a knife freak.I can't speak for him but you might give him a call and see if he might do a trade.He is on the sponsor links.
Lancaster Archery Supply sells some youth recurves for around $100.Don't know anything about them.
On the cheap just cut a hickory tree or get a piece of Red Oak from Home Depot and make a bow.With a little help on the bow forums it is easy to make something much better than anything traditional you could buy at Walmart or such.Making a bow with dad would be something neither of you would forget.If you choose to try one I'll list you a book or two and web site to help or make myself available for any questions.I'm no expert but have made a dozen or so good adult bows from Hickory and a bunch of adult bows that turned to kid bows while I was trying to learn.
Good luck and let me know if I can help.