I go to flea markets, thrift stores, and antique shops maybe 2-3 times a month. I have purchased a treadle at a flea market in almost pristine condition for $130 and a 1936 FW in pristine condition for $220 at an antique shop. Good prices, but not exactly that "wow" bargain.
After about 5 years of collecting vintage machines, I finally ran into a great deal at an antique store. I was able to purchase a 1929 Singer 101 in great condition in a beautiful Singer model 40 walnut cabinet. The price tag said $35, which I couldn't believe, but when I went to pay for it there was some sort of discount and brought the price down to $27.16! My DH cleaned, lubed, and oiled it and it runs like a dream.
Three weeks later, a dear friend saw the cabinet and said "I have a cabinet just like that in my garage. I think there is a sewing machine in it. If you want it you can have it." It turned out to be a 15-91 in a cherry (I think) model 40 cabinet! It needs the wiring from the cabinet to the foot pedal replaced, but what a gift!
Hang in there, your treasure will show up when you least expect it. In the meantime, enjoy the hunt!