I don't think that auctions on eBay reflect current demand. It is the high end and one easy access place for a lot of buyers all over the world. Even the antique malls here price lower than eBay. And their machines sit for quite a while.
The low end is usually local sales, garage sales, yard sales, some thrift stores. The audience is small and very local. I personally know 2 mayyyybe 3 people with featherweights and everyone else I know think I'm nuts for wanting an old machine. I'm a fairly isolated person with my hobbies, that's why I'm here.
We have local resellers at the antique malls that are on craigslist/thrift stores all the time looking for machines. With the ones I have seen I know they are buying them just to profit off the demand. While there's nothing wrong with this, it does take some of the fun of the hunt out of it for me. I won't buy from those guys in general.