No, not too expensive, usually there's some available on ebay, and I always contact Helen Howes for parts like these. There was or is a recent thread on a parted up 66 that was donated to a member, the bobbin cover might be available. I don't know of you quilt much, I mostly sew clothes and the odd projects like leather bike seats, faux lather, etc, uphostery and a 66 is very nice to work on. My machines have electrical motors, but I guess it's all about technique. With a treadle you have both hands free to guide the material.