If at all possible, I would do as ManiacQuilter suggested, and go to a larger quilt show. That way you can not only "test drive" the DSM's but also the longarm machines.
I bought my Viking MegaQuilter (18x8, same as a Tin Lizzie) from Sewingmachinesplus.com - they let me put it on lay-away, and I love, love, LOVE it!!! I paid less than $5K for mine, frame and all. If you look, SMP often has close-out deals where the machines have been refurbished but this is why they're not allowed to show the brand name. This is what happened with mine, but other than "operator error" problems (ME!!), I've not had any issues with mine.
Here's what they have right now -
http://www.sewingmachinesplus.com/18...m-upgraded.php
this LOOKS like the newer version of my machine, plus this one has the better frame (my frame is wooden and uses the metal conduit poles). So, this one is less than $6K. Steal of a deal if you ask me.
Good luck in your search for a quilting machine!!