The Voyager is not normally a sit down machine and it has been discontinued, I believe, at least as it was originally sold since Hinterberg has merged with Nolting. There was also a Weekender 10" machine and I believe a Quilting Bee or something similarly named. Definitely check at the Nolting web-site.
I have never seen the WOW as a sit down machine but the makers of the WOW quilter will stretch the Juki/Brother/Janome/Pfaff/Babylock 9" straight stitch only machines to 18".
The Janome Horizon 7700 is an 11" domestic machine and was being sold brand new for $2,000 when it was first released. I don't know if the price has gone up or down since then.
The ABM Innova may be able to be adapted to sitdown sewing. And the Crown Jewel by Babylock, possibly. I believe I also saw the Tin Lizzie setup to be in a table however they call it a Queen Quilter in that setup. Since the Viking MegaQuilter 18 x 8 is the same machine, it could theoretically be set in a table, also.
There was a post a day or so ago about a Juki 8700 industrial machine that is being marketed at quilters. I believe the price on it was around $2,200 setup.
Nustyle is another one I can think of off the top of my head. They are sold by a store in Stover, Missouri or in that area.
There are also older/discontinued/home-made machines that are in the 10-16" range. You may stumble across those in your research. DAQ (Design-A-Quilt) had an interesting history, Versaquilter made a bright yellow Tweety Bird and a Purple Monster.
KenQuilt is still around although I believe they recently merged with another company.