Device makers producing Android tablets probably should sit up and take notice of the coming onslaught of Kindle Fire tablets from Amazon. They look fearsome.

Amazon opened pre-orders for the new 7-inch Android tab last week after announcing the device, and according to anonymous sources speaking with AllThingsD, it currently is taking about 25,000 sales for the device every day. No one has even seen the Kindle Fire, but a lot of people want it, it seems. For its part, eDataSource is estimating the numbers to be closer to 20,000 a day, but with about 90,000 sold on day one.

As PCWorld reports, that suggests Amazon has moved a quarter million Fire pre-sales already since it was announced. And those numbers would be actual units sold, instead of the often-used and generally misleading units shipped, which is the number of devices sent by a device maker to retailers. Other device makers often use the “units shipped” metric when talking about the success of a product, but that number only measures how many devices are available on store shelves, not how popular they actually are with consumers.

Meanwhile, Amazon is shipping its Kindle Fires directly to the people who want them, so every one of those pre-orders is a real sold unit.

We expected the Kindle Fire to be a force in the tablet industry, what with its extremely low $199 price tag. That basically puts it on course to best about any other tablet on the market – it undercuts Apple’s iPad by about $300 and makes the Kindle Fire extremely affordable. Of course, Amazon’s tablet isn’t quite up to par with the big boys on the market, though: it lacks a camera and 3G Internet capabilities, and it won’t be as powerful as the iPad or, say, the Samsung’s Galaxy Tab 10.1.

But the Kindle Fire makes up for it by leveraging Amazon’s online platform and cloud capabilities, and it surely will find a lot of support from among Amazon fans.

Apart from pre-ordering from Amazon, Kindle Fires will be available at a handful of retailers as well, including Best Buy, Target and Staples. If you’re not the kind of person to just trust in Amazon and order a Kindle Fire blind, you can try one out there after the device is made available on Nov. 12.