upholstery fabric sources  

I've used this place in the past..
they were fine to deal with
http://warehousefabricsinc.com/Merchant2/merchant.mvc?Screen=SFNT&Store_...

.
Kvadrat Divina 2 (or 3 I think it is now) excellent colours, feels like felt and amazing to work with, thick but flows around corners like water.
You have to scroll down to 'fabric' and choose Divina 3.
Tonus 3 isn't bad either but is much coarser.
http://www.kvadrat.dk/textiles/collection/

reclaimed fabrics from knoll,...
reclaimed fabrics from knoll, maharam, herman miller et al.
http://www.modern-fabrics.com

Ebay!
But also PA Fabric Outlet if you're in that area (near Lancaster). They have a lot of Knoll fabrics, also some other high end mod stuff. Prices are generally under $12 per yard for most of it, rarely over $20/yd.
They sell some basic stuff from their website but you really have to go in person to see what they have. It's a pretty big shop.
They also have sales every 2-3 months where everything is half off. I've never been but they said it's very, very busy---people driving down from NYC and up from DC.
http://www.pafabric.com/

Contemporarycloth
I find they have a good selection and affordable prices (good selection/prices relation).
I meet them here at DA. They are one of the DA sponsor.
They had just confirmed the shipping of my first order some minutes ago 🙂
Sondra is very friendly and professional.
Many other places I saw or they have very expensive prices or you find just one or two interesting fabrics.
http://www.contemporarycloth.com

One wonders
whatever happened to the warehouse full of quality Boris Kroll fabrics? His business lasted through the 1970's....