The new stuff is much more expensive, because the "offshore" aftermarket suppliers aren't servicing the new design. I hope that's a temporary situation, but with the XJ out of production ... it may be permanent.
The profile of the top outer corner of the fenders is different, but the new style flares will attach to the old style fenders so there is a work-around. Bob Salemi did this with his older model XJ. He took a new-style header panel, and filled in the void at the top outer corners. Then he mounted the new header panel to the old fenders, and ground down the outer corners until they mated up with the fender profile.
He said there was one place where a very long bolt was needed, and he had to do some wirning to adapt the side lights, but the result is quite workable. Only someone who really knows XJs would pick up in the fact that it's not a complete new-style nose.
Oh, yeah -- he's running the new style flares on all four corners, with new style bumpers.