I realize this is likely outside of your price range and so I hope you don't mind I mention it, but I thought I'd post it in case there are other short riders reading this thread and looking for a road bike with very short top tube too. Luna Cycles has a very small pre-built steel road bike for sale right now that is ready to go:
http://www.lunacycles.com/36cmPrebuilt.html
It's top tube is only 46.5 cm. It's a honey, waiting for *someone* out there to ride it!