TRY GOOGLING "SOLID QUILTING FABRIC" WITH THE QUOTE MARKS. (caps inadvertent)
The well-know on-line vendors are pretty reliable. I've had mostly good experiences; some, however have rotten service though good cloth.
If you find sources who have what you want PM me and I'll tell you my good or bad.
Also, not sure if Plattsburg is near Quilting by the Lake in upstate NY; I haven't gone in several years (too pricey now)but I know they've moved from Morrisville.
Their quilt camp is usually in July/August for 2 weeks. If you're 1+1/2 to 2 hours away it's very worth a day trip. Great vendors and one of the very best quilt shows around.
I just looked it up; located now at Onondaga Community College. I see that Nancy Crow is back as a teacher this year. I love her work. All the teachers have a quilt in the show, one of the reason it's so good. She's a tough broad but I learned alot from her critiques when I took a week long class with her about 10 yrs. ago.
http://www.quiltingbythelake.com
Also, I just read the Amish suggestion. There's a shop in Indiana: Gohn Brothers; I think they're Mennonites, that sell solids reasonably prices. I seem to remember they have an on-line presence