Why not sell it here? You need to become a regular first (based on number of posts). Check the "classifieds" section of the website to find the rules.
Price of a featherweight is often very dependent on decals. The more pristine the decals, the higher the price. Where I am, featherweights often sell for about $300. If it comes with the case and attachments, $350.
The most difficult thing if selling long-distance is properly packaging the machine for shipment. Many machines are damaged during shipping because of improper packaging. To avoid the packaging issue entirely, you could advertise for local pick-up. Craigslist would be a good place to list the item for free. Newspaper ads cost a little but can also be a good place to advertise -- especially in the smaller, more local papers.
Edit: Oh, yes. Why not keep it for yourself?
I think an "antiques" store would be one of the worst places to sell a featherweight. They would want to pay you $50 for it and then would try to sell it for $400-500. Direct selling is a much better option for you, especially since there is a persistent demand for featherweights.