Almost all road bike brands will carry entry level bicycles between $500-$900. One good bicycle is the Jamis Ventura Sport, MSRPs for about $550 and carries Sora.
You could do bikesdirect.com and amazon if you know what to look for.
http://www.bikesdirect.com/primalstuff1.htm
And I thought girls end their growth spurt around 12-16... then again IANAD.