I have a Pfaff Grandquilter and it has about 10-12 inches of space. I have mine on a frame. The machine is only around $1200-$1400. The frame is about $2000. I really like my setup and have done several quilts up to queen size.
Are you looking for a machine and frame setup or just a machine with more throat space. The Pfaff machine is only a straight stitch machine so if this is to be your only machine I would say this is probably not the machine you are looking for.