I have several sewing machines. The best one for quilting is my 6600P. I love the accufeed system ( you don't have to put that bulky walking foot on)..you can see so much better with the Accufoot. I like the free motion capabilities too. For piecing, you can't beat the auto thread cutting on the 6600...I know the Bernina has this feature...but you are talking thousands more. Janome has the new 7700..I tested it...it wasn't worth paying $2500 more than the 6600.
Since the 7700 came out the price on the 6600 has gone down and lots of ladies are trading in their 6600 so there are lots of trade ins that are in good condition at the dealers. I would be cautious about Craig's list...it is OK if they have a recent dealer check up document with it, otherwise Buyer beware.
Call Brubakers and see if they have any good trade ins or maybe a new 6600P is OK with your budget. New I think they are $1400-$1600. Used are $850-$1000. You can't go wrong with the Janome 6600, it was built primarily for quilting. Brubakers has a website, but just call Amy...she will help you. Their website is brubakerssewing.com (notice the SS, put 2 not 1 in your URL) I don't work for them, just a satisfied customer.
They beleive in great customer service. Test drive a 6600 at your dealer, then call Brubakers (No tax on any machine and No shipping on new machines)
Good Luck on your Quest
Diana in Texas