I searched several months for the adequate setting; was thinking first about getting only a frame and a stitch regulator for my Juki TL-98. I found MANY buying options for a frame, a 9 inch troat machine and a stitch regulator in the 1000$ area, so I think your setting in a bit overpriced. There is a lot for sale because people end up upgrading for a larger throat.
I was very close to buy a frame when I finally found the best deal ever on ebay: a HQ 16 on a frame, stitch regulated, in wonderful condition for 2500$ The owner was the sweetest lady in the world. I finished my first quilt last week on it and I LOVE it. I'm so glad I waited and end up with such a nicer setting for not that much more. The quilting area is just perfect for me and I don't quilt anything larger than a lap size quilt. Would have enjoyed it much less with a smaller area.
So if you are not in a hurry, just wait and watch and you may end up finding the perfect machine for your need.