I have forgotten how I found this site: http://www.221parts.com/advert.htm
They are in Florida. I ordered a few things on 2-20 and got notice that they shipped on 3-1, which seems a little less speedy than most these days, but I'm in no hurry. They did communicate promptly that they had received the order and payment, and notified when it was shipped. I'll try to remember to update when it arrives.
Following up, as promised: The items arrived today, about 2 weeks after I ordered them. They were exactly as ordered and I think they'll be good to have. I got a quarter-inch seam foot, a seam guide, a darning plate and darning foot. I feel the prices were reasonable, and the items appear to be good quality.
