My wifes thought's were "I know about bikes so I should spend what I think is right for a good quality make that will last". - then I mentioned the kona stinky.
So my son has a Trek MT60, seems really adjustable (he's a small 9) it has a kickstand, I'm sure it has saved me buying a few rear mechs.
It cost £180, he now wants a BMX :roll:
In hindsight I would have gone the build from scratch route but the trek is a really solid Alu frame. And on Xmas day a new bike says it all.
I might build my daughter's bike from scratch as she'll need a new one around her spring birthday.