Where to buy maharam hopsack  

Use that interwebs thing.
Google ( http://www.google.com) will show you lots of places to buy Maharam fabric in retail quantities. Here are two:
http://www.modern-fabrics.com/store/store.php?pg1-cid42.htmlhttp://www.frelis.com/by-brand/manufacturer/maharam.html
Maharam makes a few hopsack-weave fabrics. Here's one:
http://www.frelis.com/catalogsearch/result/?q=messenger
and if you want it in red and don't need more than 5 yards, you can buy it for $12/yd here: http://www.modern-fabrics.com/store/product-info.php?pid1072.html
http://www.google.com/search?q=maharam+messenger

design within reach
I think dwr sells fabric... it's been a while since I've checked.

fastfwd, thanks for the link...
fastfwd, thanks for the link to google.
Have you used either of those sites? I'm hesitant to shop at the first place that comes up on a search. I'm wondering if anyone has found a reliable place to buy or has had a good experience somewhere.

I've used Modern Fabrics
Nice people, good prices and very fair delivery costs.

Thanks
Thanks Olive. I think I'll give them a try.

I've ordered from both modern...
I've ordered from both modern-fabrics.com and winterbeachmodern.com and both are reputable modern fabric dealers. The prices are right, they send mini samples of the actual fabrics, but they do not carry the entire line Maharam or Knoll fabric lines.

Thanks
Thanks kixrix.

Try kvadrat.dk
they should be able to help you.