I finally decided to go ahead and buy a new sewing machine. I bought the one I had been looking at at Amazon; I had a bunch of gift card money saved up, so it didn't cost me much. this is the one I got (lists price $349, I had $100 in gift cards, so it only cost me $40!) -- a computerized Brother machine with 70 stitches, most of which I probably won't use. The thing I really wanted in a new machine, besides being able to sew a tight, appropriately-tensioned seam -- was automatic buttonholes, which this one has. There were a lot of machines to choose from, but this one had good reviews. The one feature that made me choose this one was the oversized table. It came yesterday and I read through the manual, threaded it, and sewed a seam, and it worked like a charm.
I may not sit down and do much of anything with it until the weekend, but I wanted to be sure that it worked! It will be fun learning my way around it. I'm looking forward to it.