You might want to consider other options. I am! Here are some that I am looking at:
http://www.quiltingboard.com/t-149818-1.htm
http://machine-quilt-frames.blogspot.com/
http://www.easyquilter.com
I had an opportunity to try out the Easy Quilter at a show recently and really liked it. It is a little different than the others in that you spray baste your quilt sandwich first, so you need only 2 rolls (which the metal half-circles hold). Also, with this frame, the right and left ends of the quilt can hang off the sides. To do a large quilt, just split the batting into thirds and quilt the middle first. The machine at the quilt show was a Janome 1600P, which has a deeper throat and sews at 1600 stitches per minute. I really liked the high speed stitching (the guy at the booth told me to "floor it", and I did :D ).
With any of these setups, throat depth is an issue. On the website in the QB post, he mentions that with a domestic machine and a queen-size quilt (I think it's queen), you end up with only about 2 inches of quilting space at the end. With any of these setups, though, you can simply quilt to the mid-point and then reverse the quilt and quilt from the middle to the other side. (This can be done with all of these frames, as far as I can tell.)
My current problem is that I showed dh all of these setups, and he thinks he can do better. (groan......)
What I am currently leaning towards is having my dh make something similar to the Easy Quilter, but with the carriage assembly from the quilt board post above (because of the metal wheels). I like the Easy Quilter because it does not take up so much width. Figure I will start with this setup, then later when I have more money, purchase a fast-stitch machine with a deeper throat than my domestic machine. Figure my dh can make the frame setup for about $200. A fast-stitch sewing machine with deeper throat runs around $600.