Welcome. I know that Viking has at least one model that threads itself; that's the one I want. My LQS has some slightly used and new ones and the prices are good. I have Nancy Z. book on quilting with a serger and I want to try that. Plus I'm getting back into making clothes (slowly) and it works great there too. I'll include the website because its one of the view I've ever seen that shows you prices; regular and their sale price. I like buying at the LQS because you'll get a warranty even on used ones plus you get hands on training; which for me I couldn't put a price on. I learn by doing, which is why I normally struggle thru and it takes me more than double the time needed to figure out what I needed to know. Trying to figure out what some of these manuals are talking about makes me what to give it up. Good luck with your search. By the way I now own 3 Viking machines and they are great.
This link is for the new ones:
http://www.bellafabricsva.com/quilting-machines.htm
this is for the used ones:
http://www.bellafabricsva.com/gently...w-machines.htm