I've bought stuff from this guy and been quite satisfied:
NY PRO AUDIO PROFESSIONAL AUDIO CABLES & SOLUTIONS - Home
These guys are big too:
eBay Store - www.SpeakerRepair.com: Patch Cables - GLS Audio, Mic Cables - GLS Audio, Banana RCA Plugs -GLS Auido
Really, if you search Ebay "Pro Audio" -> "cable" -> "bulk" a bunch of places come up. You can luck into rolls from closing studios real cheap too, boxes full of patch cords etc. For short patch cables and home recording, I use Bill Lawrence's solderless cable kits. He invented the idea, his former employee George L "borrowed" the idea and charges twice as much, but the Lawrence cables work fine. Bill's website is getting revised, but it's like $50 for 50 feet of cable and 16 ends, if I remember right. Call Becky, and you might get to listen to Bill gas about the old days.
Contact Bill n' Becky