My opinion....ebay has millions of viewers and usually brings several times what a machine would sell for locally. I would check with a local Bernina store, or ask at your LQS. This is true for much older machines than the 1530, anyway. I assume that you would be able to try her machine, and that is worth a lot, however. The accessories and feet are valuable, in themselves.
There is a 1630 for sale at a dealer in central NY for $699, but that includes free lessons and a 1 year warranty, a 1 month 100% trade in and a 1 month satisfaction guarantee. There is no cabinet, of course. If you have room for it and it expands for quilting, that would be valuable in itself.
You might check the Yahoo group, "Sewitsforsale", to see if any have sold lately.
Good luck....I hope you get a good deal!!!