If you really had your heart set on buying that $500 US flame-thrower from tech entrepreneur Elon Musk, you're too late.

Musk tweeted overnight that all the 20,000 flame-throwers being sold by his Boring Company have been snapped up

The devices sold out in just days after Musk posted a video on Instragram of him messing around with one of them. The sale started shortly after the video went up.

The whole thing apparently started as somewhat of a joke when Musk tweeted back in December that if The Boring Company could sell 50,000 hats the firm would start selling the flame-thrower.

The sale also drew criticism from a California politician who said he would introduce legislation aimed at banning the flame-throwers.

"We don't allow people to walk in off the street and purchase military grade tanks or armour-piercing ammunition … I cannot even begin to imagine the problems a flamethrower would cause firefighters and police officers alike," state assemblyman Miguel Santiago of Los Angeles said in statement.

Musk has argued that the flame-throwers are legal.

In a tweet after he announced that the flame-throwers had sold out, Musk said they will ship with a complimentary Boring Company fire extinguisher.

The Boring Company is Musk's venture to dig tunnels for a system that would move people underground in their personal cars instead of in subway cars.