Digital BW, The Print

Alphacare from Bainbridge will likely serve your purposes. Any rag mat will come in several shades of white, from a very pure, bluish white, to a softer, "spanish" white, which is somewhat yellow. Call the suppliers below and ask for samples of mat board. Both have kits that they can send you. 

Bing at matcutter.com sells custom cut and pre-made sizes. From small amounts to high volume. Very good turnaround, very consistent quality, easy website to order from, or you can call and talk to Bing or Nancy personally. NIce people to deal with. (Alpharetta, Georgia)

Mark Rogers, at framedestination.com. Another good source for mats and frames, and some framing equipment. Another good website, excellent service, excellent quality. (Dallas)

Both of these sources serve demanding professional and retail markets, and will also cater to the individual artist.

Another good source for mats and frames is americanframe.com, in Toledo. 

Michaels is probably the last place I would go for framing, as their prices aren't really all that cheap, even when on sale. You are better off linking up with a local framer if you want to buy local.

Jim Parker
parkerparker :: design | photography
http://www.parkerparker.info
@dakkid / twitter