I’ve just come across a site that sells and maintains used Apple Newtons. I forget who sent me this link, but I’m glad they did. Newton Sales sells used Newton 2100 and Newton 2000 with various options, but what’s even better is that you can also get after market hardware components for the Newton.
This thing was killed off by Apple over 13 years ago, and yet people still use it. The first Newton was sold in 1994 and the line was discontinued in 1998. There were a total of 5 models and a netbook (no, seriously).
You can get Newton Sales to install a headphone jack or USB port, upgrade the CPU, fix the back light, or recover the data. (With the right software you can even get the Newton to support text-to-speech.)