Yeah, you're probably right about the salmon from the Copper River. Here in Charlotte the couple upscale fish mongers tout it in season. Upscale chefs tout the salmon from this particular river. The result is people paying stupid money for a fish.
As for the watermelon, you can do an online search and easily figure out its cache. NPR did a piece on it, for example.
Down in South Carolina rice still grows. It's called Low Country rice, I think. Upwards to $9 a pound.
What with all the nouveau cuisine, celebrity chefs, cooking shows on TV 24/7, what happens is a family farm grows a specific variety of anything and it's discovered by a food writer who touts its wonders. Other food writers chime in and then the chefs begin featuring it and next thing you know, a tomato, for example, that would retail at a grower's only market for $3 a pound, jumps to $7 a pound.
He looks at you like you owe him money.