The man who runs Freedom Included, Inc. (the seller of the laptop through Amazon) works at the Free Software Foundation with RMS. I don't think RMS will have trouble getting a new laptop.
I would donate to anything Stallman related anytime. But I am not quite sure if this would be in his intention. Are there any public infos about his personal/financial situation?
If you actually do this you'll either have to get it elsewhere or not tell him it came from Amazon. Stallman recently wrote about how we should stop supporting Amazon. I seriously wonder if he'd accept if he knew where it came from.
Also I found it on Amazon, with Prime: http://www.amazon.com/Screen-Lemote-Yeeloong-8101_B-Netbook/... $450.
If one of the known / trusted HN elders decides to pool the money, this seems doable.