I am no expert, but there are very experienced frame quilters on the homequiltingsystems list at
http://groups.yahoo.com . I would definitely join that group, check out their files, and perhaps solicit advice from the quilters there. A quick search on the posts there turned up at least half-a-dozen comments on this setup.
From what I know, that is a very good price. The homequiltingsystems group has a "for sale" section; there was someone on the homequiltingsystems list selling the Inspira frame and Qbot for $900 in November (machine not included). Not sure how much the machine is.
I had the opportunity of seeing a Qbot in action at a store. The owner had just quilted a large fan circle (maybe 10 or 12 inches in diameter). What I didn't like was that she had to do it in quarters. With a computerized program I would much prefer that it be able to do the entire circle without my intervention. I gathered from that demo that the Qbot has size limitations on patterns.
I'm pretty sure the Grandquilter is a mid-arm machine rather than a long-arm. The files at homequiltingsystems would help you understand the difference. I think the Grandquilter harp area is about 13 inches whereas a longarm would be 17 inches or so. The problem comes in if you are quilting a large quilt. As the quilt gets done, the takeup roll of the quilt gets thicker and starts limiting the area actually available for quilting. While you can quilt a 12-inch pattern at the beginning of the quilt, towards the end you may be limited to only 6 inches or so of space for a pattern. That is the big limitation of mid-arm machines.
There are advantages and disadvantages to every setup; you have to decide what is the most important to you.