I bought a bag/tote at Michaels last summer when they had a huge sale as well as a 40% coupon.
Anyway this one is probably supposed to be used for scrapbooking but it works great for a knitting bag. It has a large, center opening with 2 slender pockets for paper/patterns/whatever else you need them for, one on each side. It also has numerous small open pockets on both sides with 2 covered pockets on one side and a larger covered pocket on each end.
I have enough room in the center area for yarn for a whole sweater and room to spare!
Bummer is I can't remember what brand it was.
It's black material with a flat, stiff bottom, and handles that are long enough to carry over your shoulder without being too long. I have enough room for my wallet, phone, etc. as well as knitting needles, yarn, and all the other things that go with knitting.