Timberhawk Strike $379 brand new. Excellent customer service and super nice bowyer. He will answer any question you may have.

I would suggest a vintage bow. If things don't work out you can sell it for what you paid for it if you don't pay too much to begin with.  Any of the well know makes would work. Just make sure the draw range is right and the lims ar't warped. It would be best to have your nephew try it in person to see how it fits him and if it suits his draw length.