14 feet isn't a huge boat. It might be reasonable to get a kit from Sailrite and sew your own. I've read reviews from people who have done that and are quite pleased with the results. I plan on making a new mainsail this winter. Another thing to consider . . . are you sitting? Poly. No, really. Look for poly sailiors. They literally make sails from tarp material, Tyvek, stuff like that. I think just because they can. At least you'd be making a statement!
Can't help. I never even knew used sails were a "thing" when I was sailing in California.
I'm in Maryland now. I can vouch for Bacons. If they have a sail with the correct hoist and foot dimensions, and they say it is in good condition, you will be impressed. I can't imagine shipping would be too much.
They didn't specifically list anything for an O'Day Javelin, but they do have small sails. Have a look.