I make Teddy Bears and have poly beads that I use with poly fill to fill them. I have a 10 pound bag and I bought it about 3 years ago, but I didn't pay very much for it. I don't remember where I bought it. I know I "Googled" it and I think I bought it from an Amazon person. Not the Amazon site itself, but the people who sell on Amazon.
I usually buy most everything, except fabric, from Amazon sites. They are the least expensive so far. So try that. I know I wouldn't pay very much for the bag. I know myself and I know I wouldn't spend too much for it. I think that is your safest bet.