I think Craigslist is worth a look as well. Every now and then some there are some great deals to be had. For example, I sold my lightly used Specialized Tarmac carbon fiber bike for $450 a few months ago. If nothing turns us on CL, Bikes Direct bikes offer a good value at their price point. I have helped a number of people set lower priced ones up over the years and they were fine. One girl rode her sub $300 bike in a few triathlons before upgrading. A $350 BD bike is what got me back in the saddle after a layoff about 10 years ago. Another option is Bike Island. They partner with BD and sell their scratch and dents. They offer free shipping as well.
https://bikeisland.com/cgi-bin/BKTK_...=Bikes:%20Road
You have to scroll to the bottom of each bike's description to see what the defects are. Typically it's just scratched dropouts. The more common sizes sell pretty quickly, so check regularly.