There's a 2006 Specialize Junior bike listed on eBay for smaller riders / youth riders. I have no relation to the seller, but I'm asked about really small bike options occasionally and these aren't sold often. Seller says <100 miles, a few scratches.

These bikes have 700cm wheels, Shimano 105 group, 165 crank arms, with short top tube and low standover height.

Current bid is $511.

http://cgi.ebay.com/2006-Specialized...ht_1225wt_1111