No manufacturers of climbing rope over here that I'm aware of. Never seen even one Japanese-made cord on a store shelf. It's mostly all Beal and Mammut, with a few Edelweis and Edelrid. No Bluewater or other U.S. makers.
I don't actually have any specific information on the high pricing of imported ropes, but my guess is that it's a combination of factors, including shipping costs, taxes, and the willingness of retailers to impose substantial premiums because they operate in a relatively closed market and their buyers' demand is pretty price inflexible. (Shipping costs and language barriers pretty much block internet purchases from overseas for most Japanese climbers, although I've been known to have a package flown over from time to time.)
On the other hand, from what Mike is saying about R&S, it sounds like the prices are getting up there over in the States, too. I guess the raw stock for nylon is petroleum; so could it be that rising raw materials costs are feeding through the stream even in the U.S.? Doesn't really sound persuasive, though, because how much petroleum does it take to make a rope...?