I have bought 2 for under $20. including the shipping cost with the first one, neither are the cheap brand one either. The first one I got many, many years ago off ebay from one of the sewing part company that many here buy parts from still. Yet when they sell them on ebay the price is far more reasonable. The last one I picked up cause 2 are better then one right? lol that way when I can leave them on two different machines! Well anyway the last one I just got a couple of weeks ago with metal feet Alphasew for $13.86 at one of the local quilt shops. It is also the Quilt Shop Hop so I saved 15% from the normal price of $15.99. They still have a high shank and another low shank left. So look at your local Quilt Shops too!
Watch ebay and here is the link included, just when you bid remember to add the shipping cost when you place your bid and I'm sure you will get one for under $20. Also remember Featherweights use the low shank foot.
http://www.ebay.com/sch/Feet-/41245/...&_skc=50&rt=nc