Credit cards can also be used on the startup's new 'buy' page, and the firm says it has put in place the "standard logistics" for checking out and shipping anywhere in the US.

Previously, 21 was selling the devices via Amazon, which does not accept bitcoin as payment.

International orders cannot yet be processed, however 21 says it is "working hard" to expand support outside the US.

For now, users that select international locations at checkout will be asked to provide an email address so the firm can notify them when that option is available.

For bitcoin buyers that would prefer to remain semi-anonymous, the firm has also announced  a private checkout option. This lets purchasers pay with bitcoin, without providing a name, and request shipping to a PO Box. 21 says it will address the package to "Postal Customer", as USPS rules allow.

21 said in a blog post:

"It’s by no means perfect –  we’ll still need an email address to get in touch, among other things – but when combined with the right measures on your end this process is a first step toward a more private and decentralized Internet."

Image via 21 Inc