http://www.pkwalsh.com/
They will fit and sell natural and synthetic wigs, can be expensive.
For cheap wigs
http://www.paulayoung.com/
I found them very comfortable, a good match, down side they don't have daily
wear well, but cheap enough to replace.

<< Does anyone have recommendations for places to purchase good quality, well
fitted,  synthetic wigs for a chemotherapy patient (32 year old woman)?
Anywhere within 50 miles of Worcester would work (including Boston,
Hartford, Providence, Springfield), though obviously Worcester MA would be
most convenient.  Thanks for you help!

"guess who" provided recommendations of stores.  Most stores sell several
different types.  I would like to recommend one particular type--- Rene' of
Paris.  I found the wigs by that company to be the most natural looking --at
least they were 3 years ago.  Best of luck!