I think sometimes people price things based on how much their credit card bill is......or how much they want to spend on their vacation trip. They don't do any research, just make up something. I went to a yard sale last weekend and there were 7 white plastic sewing machines, Kenmores and Brothers, and when I ask "how much" they said some lady from a local college thought they were worth $75 each. I just shook my head. They were dirty and some broken!
On the other hand, I got several sets of attachments,and other parts, bunch of thread, pair of slacks, nice vintage fabric pile and two charming long aprons that look like 1900 fabric....for $10.