Most LQS carry a good quality cotton broadcloth. Comes in solid colours and is comparable in quality (and price!) to any good quilting cotton. The Kona solids are considered high quality 100% cotton broadcloth at my LQS.
Most fabric stores also stock an inexpensive poly/cotton blend broadcloth for all sorts of general usage. It's usually just $1 or so a yard.
Here's more info, for those of us who just can't get enough:
http://en.wikipedia.org/wiki/Broadcloth
This is interesting:
http://www.wisegeek.com/what-is-broadcloth.htm Guess there are fabrics we refer to as broadcloth that really aren't in the classic sense of the word.
Chele, they do still make it out of wool. Pretty pricey though and used in suitings and upholstery. I'm sure some of it feels absolutely wonderful.