Check Craigslist every day and make sure you search for the right size and one should come up if youre persistant. The most important thing to pay attenton to is the components especially the front derailer and shifter because if you go cheap your'e gonna eventually end . I.E Shimano Tiagra, Ultegra, Dura-ace all good. I got a Giant OCR 2 on CL for $500 and I love it.
I just bought my first road bike for commuting this summer. I went the hipster route as my commute isnt very far (5km) and its pretty flat. Ive always paid top dollar for my bikes i built a black market mob for dj'in and spent around 3k on it...with my commuter i went as entry level hipster as possible picked up a mongoose sinsure for $149 lol will upgrade parts like the crank and bb as they brake and ill ditch the freewheel and flip it over to fixed most of the time...but for $149 i couldnt say no for a commuter.
Looks decent for the price.