I'm afraid that it's difficult to answer your question since affordability is a relative thing. For instance, take West Roxbury, a great community within the boundaries of Greater Boston. It's known for its family-oriented neighborhoods, commuter rail stations and fun shops and restaurants. Single-family homes though can be found from the high $300k's and far beyond. Is that what one would consider affordable? Perhaps but as I said, it's all relative.
If you need help narrowing down the field of options of communities in and around Greater Boston, drop me a line. You can message me directly through my website: http://www.GoHomeWithMichael.com.
And, if you'd like what to see what my clients have to say about me, check out my recommendations here on this site.
Michael Pallares, Realtor, ABR
However, there may be some diamonds in the rough here and there for you.
Brookline, Newnton, Watertown, Arlington, and even Cambridge.
best of luck.