I've been waiting and watching for a couple of years for "my" featherweight. I didn't care much about the guts of the machine - those, I can clean and repair and in the case of electrical components, replace.
But good paint and decals aren't easy (or sometimes even possible) to fix, so I wanted the machine to be in excellent condition, cosmetically. And I set an upper limit of $200.
If you want your machine to be freshly cleaned and refurbished and in perfect operating order when you get it, your upper limit can be a lot higher. $400 isn't too expensive at all for a Featherweight in this condition, especially if it comes with a full set of attachments and case. :)
I passed up a LOT of 221's, mostly because the decals were too worn. But, I also saw a lot of machines ridiculously priced for the condition they were in - some were missing the foot control and cord, some were missing all the attachments, some were missing the case.
I finally found one with paint and decals in really good condition for $200 last week. It has electrical issues and it was dirty inside, but I'm replacing all the electrical and cleaning it out, so for a total of about $350-375, I finally get to add a cute little perfectly-running Featherweight to the herd. And to top it off, it's a Centennial. :)
Don't give up. Figure out how much work you will do yourself, how much you are willing to do to it to get it restored, what condition you want it to be in and what's the highest you want to pay for it. Eventually one will show up at a price that works for you. :)