Microsoft on Sunday slashed prices on its Surface RT tablets by as much as 30%, with the entry-level 32GB model selling for $349.

The 64GB Surface RT was also discounted by $150, and now sells for $449, or 25% off its former price.

When Microsoft launched the tablet, it sold the 32GB device for $499 and the 64GB configuration for $599.

Microsoft started selling the Surface RT at the lower prices Sunday, as did some of its U.S. retail partners, including Best Buy and Staples. On its website, Staples noted that the discounted prices are valid until July 20, and only while supplies last.

Microsoft's website, however, listed no caveats, hinting that the lower prices might be permanent or at least will be honored for longer than one week.

The prices are another attempt by Microsoft to clear its existing inventory in preparation for a second-generation line of Windows RT devices. Previously, Microsoft had launched multiple deals to rid itself of the poor-selling tablet, most recently in June when it slashed prices by 60% in a bid to get universities and K-12 schools to buy the device.

Earlier, it kicked off a buy-a-Surface-RT-get-a-free-cover deal that ran until June 30. And at several conferences, including June's TechEd North America and this month's Microsoft Partner Conference, the company sold attendees a 64GB Surface RT for $100, 83% off list price.

Today's sale prices were nearly Microsoft's cost, which according to estimates of the tablet's component prices, runs the company at least $284 for the 32GB Surface RT.