HP’s Slate tablet, one of the first high-profile rivals to the iPad, has sold out due to “extraordinary demand.” That sounds like a stunning success until you discover the company has only made 5,000 of the device.

According to Engadget, the extraordinary demand actually took the form of a total of 9,000 orders. HP is said to have rehired production staff and is now offering a $100 rebate to customers who made an order but will have to wait as long as six weeks to get the product.

If the figures are true then, bearing in mind that Apple sold 7.5 million iPads in its first six months, it’s fairly safe to say this edition of the Slate is not going to be the big contender. That never seemed likely anyway (at $800, it was too expensive for the consumer market, without offering business users enough benefits to make it worth getting in place of a netbook) but it’s stunning both how few people actually wanted to buy, and even then, how HP underestimated demand.

The figures do appear to explain quite a lot about the pattern of events of the summer. The Slate had long been known to be in development but was slow to arrive. At first, rumors were that Microsoft was struggling to get Windows 7 working efficiently on the tablet. Then, after HP became the surprise winner of the battle to buy Palm, with the company’s WebOS operating system the apparent main target, the rumors had it that the Windows version of the Slate would be ditched. Indeed, so skeptical was the tech community that leaked videos of the device were dismissed by some as a hoax.

That proved not to be the case, but it’s now clear HP had little expectations of any success with the product. (If it did, it would be a major problem now that any new buyers hoping to purchase a Slate for Christmas delivery are out of luck.) Frankly the whole situation read suspiciously as if the company simply put the product out there because it couldn’t bring itself to ditch the work it had already done.