Bitcoin businesses are booming, especially now that 42% of Americans know what Bitcoin is — but there remain few businesses as revenue-rich as Bitcoin mining development.

Background: Bitcoins are mined by computers unscrambling blocks of "hashes" or complex strings of numbers and letters. This tends to be an expensive and labor-intensive proposition — the fastest miners now cost thousands of dollars, and they eat up lots of electricity and manhours of setup.

We recently reported that Knc Miner, a Swedish developer of Bitcoin miners, had sold $8 million of its latest model, the Neptune, in 24 hours. When it drops in early 2014 (the date remains a bit amorphous), the Neptune could be the most powerful and efficient miner in the world, depending on what the competition looks like at that time (it's impossible to say how many Bitcoins it can mine because the mining difficulty rate, which goes upward as more Bitcoins are mined, will have changed when it's released).

Today, we got new figures on Neptune sales: the first 1,200 Neptunes were sold exclusively to existing customers, at a price of $10,000 for a total of $12 million, Ian Chaffee, a press rep for the company, told us in an email.

The next batch of 1,200 were sold to new customers for $12,999 each, for a total of $15,598,800.

That gets them to a grand total of $27,598,800, excluding taxes.

The figure nearly matches the company's entire revenues for its first seven months of production and sales of its earlier models, Chaffee says.

It's not clear how the margins on one of these babies is — Alex Lawn, a KnC employee who recently came by BI's offices to demonstrate an earlier model, would only tell us the retail price is enough to cover the costs.

But it's a sign of how far Bitcoin's come.