Hewlett-Packard has finally discovered the magic price point for its TouchPad tablet: $99. The tech giant announced the new low price for the 16 GB model of the recently discontinued device over the weekend, also dropping the price for its 32 GB version to $149. Retailers such as Best Buy, Staples and Walmart followed HP’s lead by offering TouchPad fire sales of their own.

The response: overwhelming. According to PC World, many retailers had sold out of the devices by mid-day on Saturday. By Monday morning, the TouchPad had climbed to the No.1 spot on the Amazon best-seller list for electronics. Expect the selling frenzy to continue this week: HP said on Monday it intends to deliver more of the tablets until the supply runs out. HP originally launched the smaller model with a $500 price tag, but reduced it to $400 soon after its July 1 release in an attempt to spur demand.

Separately, HP launched a new desktop on Monday, days after the technology company revealed that it might spin off the world’s largest PC business — part of a wrenching series of moves away from the consumer market, including killing the TouchPad. HP billed the new computer — the HP Compaq 8200 Elite All-in-One Business Desktop — as the “first all-in-one PC” aimed at corporate and public sector customers.

Is the patent arms race over in the mobile phone sector now that Google has announced it’s buying Motorola Mobility Holdings? Reuters correspondents Poornima Gupta and Bill Rigby take a closer look in a new analysis: “The bubble in mobile phone technology patent values may just have popped. Now that Google has agreed to buy Motorola Mobility Holdings — scooping up a trove of 17,000 phone-related patents to give itself some ground to defend its Android operating system — the most motivated buyer looks to be off the market.”

Skype is beefing up its mobile communications services. The Internet calling company said on Sunday it was buying GroupMe, a New York-based startup that lets people communicate in private groups over cellphones. Terms of the deal were not disclosed.