sometimes on eBay. sometimes direct from the manufactures (particularly in China if I am willing to wait 10 days because they have great prices), sometimes from Free Time Hobbies online, sometimes from Amazon, sometimes from Hobby Town stores.
And no, there is not a 1/350 scale Ford out yet, or Zummwalt, or Queen Elizabeth I am surprised and disappointed that none of those are out yet.
I am thinking of buying a 1/350 scale Nimitz and converting her to a Ford. I did that to another Nimitz model to get the Ronald Reagan and it turned out really well: