Has anyone used, or know of anyone who has used, the Bailey 13-inch quilter? I have only read about it on the internet. I really want a mid-arm quilter (I know I can never afford a longarm), and this one more fits my budget than most I've read about. Does anyone use any other brand of mid-arm that they would recommend?

There are some threads on here about Baileys. Try the search for Baileys.

There is a Bailey owner group at yahoo. You could sign up and post any questions you have on the Bailey there. Theirs is a very active group of folks and are happy to answer any of your questions. I have a 15" Bailey, without the stitch regulator. Have had some issues, but am getting there! It is a very stright forward uncomplicated machine.
It had the arm length I was seeking and at an affordable price tag. Without all the bells and whistles, there isn't much to go wrong with it. Just about any sewing repairman can work on it, should the need arise. I have done about 4 quilts with mine so far.

I have the 13" and have been very happy with it. I just do personal quilts, none for anyone else, and I tend to make large throws, not bigger quilts, because I just like the throw size. It's been a joy to work with and the price was very reasonable. I couldn't justify much more to only make my own quilts.

Also check out www.pennywinkleranch.com. Their machine is very affordable and has a stitch regulator available.

I might add that you can get a stitch regulator with your Bailey. I just chose to wait and see if I really needed it first. So far, I've done fine without one. Personal choice.