I'm lucky. I have to travel to Anchorage and Fairbanks on business once or twice a year. I make sure to hit the local shops that are licensed to sell the stuff. I pick it up for about $50 a pound, bring it back and cut it up to suit my needs. I usually get 3 to 5 pounds at a time, based on what my budget can handle at that particular time.
Sometimes I have a good selection, which is before the dealers from the lower 48 have snapped up all of the best stuff. Sometimes the selection is thin, because I got there after the dealers have picked through it all. I can usually find some nice stuff though, no matter what the selection is at that time. It just takes longer, if it's been all picked through. I've picked up some mammoth bone and mammoth tooth also, as well as a "step buffalo" knuckle joint. The step buffalo is an extinct relative of the american bison that lived up to about 10,000 years ago. The bone I have is a real nice soft chocolate brown color. It's rather small, but should make a real nice inlay on one of my smaller knives.
So, if you go on vacation to alaska, or on a business trip....you can find some killer deals up there. A one pound piece is about 3 to 4 inches across and about 8 to 10 inches long, depending on how wet it is. You can get quite a few handle pieces out of a pound. Usually you have a lot of material on the inside that can be scrimshawed too.