I believe thhere are a couple of ebay stores too that sell them with a "buy now" option. I have some other links too I can find if you want. Whats your max price? I can narrow down the list that way if it helps?
id say my max would be around 15 a can if they are if god shape. i found this site that sells them for about 10 after shipping is included. has anyone bought anything from them http://www.armygear.net