There ARE sites that advertise long arms/mid arms/ quilting systems. I have purchased an HQ16 and a Gammill..and sold the Gammill when I purchased my Innova (I was on a JOURNEY! lol. I am done now...hehehehe)
Here are links to the two sites that I used. You need to pay a small fee, but I sold my Gammill in 3 weeks for what i was asking for. It helps to be in a metro area. (not that you can move or anything..just more people that might want a quilting system.
http://www.houseofhanson.com/formerlyowned.html#Ads start here
http://www.longarmuniversity.com/machines_for_sale.htm
Quilting on a longarm is not for everyone. Its ok to change your mind. ( I did..THREE TIMES! lol DH was very diplomatic..never rolled his eyes, not once. He IS glad I have found what works for me tho.)