You can either buy it through your pharmacy or order it from SHS. Just type in shsna.com and call them. you need to give them some details over the phone to set up an account. Through SHS, you need to order 2 cases min but in the pharmacy we were able to buy separate tins when we were trying it.
If you are in the US, which i think you are, then the newer cans are the golden ones and it says new formulation on them. If you go to website, then you can see them. (the old ones are yellow).
If you are outside the US, at least in Spain, the cans continue to be yellow, just the same as the old ones, but the new batches were made starting Oct 2005 so you just need to look under the cans for the date