Bicycle Austin forum

I would say be patient and keep looking. 
Put your own ad on Craiglist that says
"Want to buy a good road bike for $100 or less."

The bicycle in the picture there looks to be an obsolete design frame
that was common in the 1930's,  worth about 10% of the asking price.
Look at garage sales,  the Goodwill,  and  if you are driving around out in the country
look at resale shops or "antique" stores in small towns.

You can get a much better road bicycle than that for $100,
even a 40 year old one.
Local department and outdoor stores have cheap bikes but many have poor finishes
that will rust and corrode after a few years. 
A 40 year old Peugeot will probably still have the original parts and paint.

You could always just ride the mountain bike,  I like them around town.
Check the tire pressure and be sure they have enough air in them.
                                                      Good  Luck