I have a Korg N1R, the rack mount version of the N1. It has a vast array of sounds, although the way they are arranged makes them difficult to find. Might be easier on the N1 with the buttons. I like the Piano sounds and the layered piano and strings is nice. It doesn't have nice color display like newer synths, but its usable. It has a serial port that you can connect to your computer, but that doesn't function anymore under the newer Windows versions.
Make sure it comes with a manual. AFAIK, the manual is not available online. Like most Korg manuals, its a difficult read, but its definitely better than nothing.
If you want to record the N1 sounds, you have to record them onto an audio track.
You can also record MIDI and play it back through the N1 and record that output onto an audio track.
There is an INS file that you can find on the web that will help you use it inside of Sonar. It also has a General MIDI set of sounds.
There's one on eBay for $375. That sounds like about the right price if its in good working order.