My first long arm was a Tin Lizzie 18. The machine itself ran fine, was very easy to set the tension and was not fussy at all about thread. The stitch regulator was another story. Could not keep it operational. I finally learned to quilt without it. The frame was the older style, without a dead bar. Advancing the quilt was a PITA. I traded it in on a HandiQuilter Avante (18"). The frame is much sturdier and has a dead bar, and the stitch regulator actually works. I would make a list of what all is included in the price. Make sure that you look at the stitch regulator, and frame. Many Sweet Sixteens are sit downs, or come with a 'mini' frame.
Also, are you comparing prices from US or Canadian dealers?