I went to one of those sales, just because I was curious. And because I'm a sewing machine mechanic, and want to know what to tell the ladies when they call about them. It's a Singer, with a plastic bobbin holder. The man sets the stitch length as long as it will go, and sews through a lot of thicknesses of fabric, and a big chunk of leather. It looks really impressive. But, when I've had those machines in my classes, they are the machines that have problems. I'd say they are worth $129, but that's not saying much. And there's not really any warranty. When asked, the man said, you'd have to take it to a Singer dealer for warranty service. However, the local Singer dealer has no obligation to give you any warranty, if you didn't buy it from him.
In the shop, I can't tell you how many times we get those plastic bobbin cases with needle holes right through them. They just aren't made to sew on heavy fabrics. They get jammed, the needle goes through them, and they are damaged. Sometimes we can "polish" them, but the thread catches on them, and they sound terrible until we replace them.
That Singer might be alright for piecing quilts. But you'd never want to run over a pin, and you wouldn't want to sew anything too heavy.
I don't know how he makes that cheap Singer look so good, but I think there's a gimick involved.