I have a Designer 1 as well, and love it, it has the floppy disc, which my computer will format for me.
The price seems high, check ebay for price ranges, I know you are getting from a dealer with someone nearby to service it. But remember that machine has been out of production for at least 5 years then the SE version came out.
It is a solid machine and I love mine, but I know mine is not worth that much on a trade. I was going to trade it in on Diamond and they won't give me much for it, so decided to keep it along with the Diamond. And I still use it alot.
Happy shopping!