That sounds like a good price to me. I have the Sapphire 850 and I love it. If the integrated quilting platform is the Fab-U-Motion system I'd give it a good try before you buy it. I have it but am finding I can do just as well with FMQ.
for machine quilting the largest the throat opening, the better and easier to quilt on.
The Sapphire 850 has a 10+ inch throat.