jts007,
My brother had a 97 Ultra that I got to ride on a fairly regular basis. I have to agree with some of the other posts in that there is just something special about riding a 680 triple. I loved it. The power comes on smooth and keeps building. Oddly enough, it actually started easier than any of his domestic twins. He had no problems with his and I'm guessing he had over 5,000 miles when he traded on a new XC.
At $900, you probably have some wiggle room to do a little maintenance on it. There has been some good advice in this thread regarding things to look for.