http://elpetro.gob.ve/index-en.html
You can buy it on the official website. It is NEM based at this point so you will need to create your own wallet.
Keep in mind that even though their website allows US citizens to buy it, you cannot and should not buy it if you are a US citizen, or you will be committing a crime by violating US sanctions, which carries a fine of up to 1 million dollars and 20 years of prison term.