The Offer
One of the criticisms of OLPC has been the large million-unit purchase minimum. To be fair, they are dealing with governments. However, OLPC has had trouble meeting the sales numbers they had hoped for, which presumably led to the Give 1 Get 1 offer.
One gives $400, gets one XO computer and the rest of the money is used to get a child in a developing country his or her own little XO. It's a good introductory offer for fans of OLPC in participating regions yearning to get their hands on this revolutionary little laptop.
Negroponte had mentioned the possibility of an offer like this before, although at the time he theoried that it might not be the actual XO laptop on sale, but rather another laptop incorporating the XO technologies. The current offer seems much more attractive. However, it is very limited in scope and time.
Sales

According to OLPC, sales begin on November 12, 2007 and will be available only for a short period. It's not even assured that everybody who orders within that time frame will receive an XO laptop, though we are hoping this is the case. Regardless, this is a one-time, introductory offer, and OLPC needs a more long-term, less expensive sales offering.
Whatever way OLPC chooses to sell the XO laptops is entirely up to them. A direct sales model would probably serve OLPC best, as they would not have to deal with as much additional overhead. On the other hand, in-store sales may reach many more potential buyers and end up being the more profitable route. OLPC may also choose to sell in bulk to organizations for an additional discount. But what is imperative, is that the XO laptops be available for sale individually, and so accessible to the average consumer.
Pricing
As far as pricing is concerned, $400 is not bad, considering that half or more of the money will go towards the project and procuring an XO laptop for a child in a developing country. However, it becomes a significant barrier when one considers larger purchases, both by individuals and by other organizations, such as schools, desiring multiple units.
Instead of the Give 1, Get 1 offer's markup of about 100%, a smaller markup akin to 25-50% would still provide OLPC with a significant source of funds, while broadening the appeal of the laptop and removing the price barrier for most individuals and organizations. This would be a win-win situation for both OLPC and consumers, as it would be easily accessible to most, and provide OLPC with a larger amount of funds from increased sales.
As the XO laptops become cheaper to produce, OLPC may even be able to keep the original price point while increasing revenue from each unit.
Availability
The Give 1 Get 1 Offer appears limited to the United States and other particualr regions. Though it would be unrealistic to expect immediate simultaneous world-wide availability of the XO laptops, sales of the XO laptop should eventually be available world-wide, as the XO laptops have world-wide applications and appeal. In fact, XO laptops, by design already support many languages and regions.
