Know any good window covering suppliers?

I have been fortunate in the last four years to have good relationships with my window covering suppliers. My biggest problem has been getting good discounts from some of the bigger companies because I am a relatively small volume business. Should that disqualify me from better discounts? Other companies don't think so and charge me the same as their big accounts. How have other companies dealt with this problem? I would like to buy more from one of the big brand names but don't for that very reason.