This is a 2007 model. The current 2011 model runs about $400 (though they've managed to shave about 4 ounces off in the last 4 years). Scored this for $100. Needs a wee bit of TLC, but nothing major. Whoot!
The only other lightweight kid's bike I've found is made by Islabike in the UK (Shropshire).
And I'd have to go to Shropshire to get it. It's about the same prices as the Redline (£250), but it does come with a 7-speed derailleur.
I think the next step up will be a kid's road bike, like this Islabike Luath: