OLPC launched the two-for-one programme on 12 November as part of a two-week promotion to increase awareness of the laptops.
The goal is to sell the laptops in bulk to governments which will then deploy them to children in remote or impoverished regions.
OLPC founder and chairman Nicholas Negroponte said that demand for the promotion prompted the group to extend the offer until 31 December. The group estimates that the promotion has yielded donations of $2m a day.
"In the past 10 days, we have experienced an outpouring of support from the public that is truly gratifying and encouraging," said Negroponte.
"We want as many people as possible to have the opportunity to act on the giving spirit of the holiday season."
After 31 December the programme will switch to a 'give-only' donation model and consumers will no longer be able to purchase the machines for their own use without placing a bulk order of 100 units or more.