wether or not its worth it to you is all in the eye of the beholder.
Like I said I paid under $400 for mine. something like $380 to be more exact. Its such a huge difference and for that price it was well woth it too me. I cant seem to find them for that good of price anymore b/c Im looking for another set as well.
$509 though IDK if ID pay that. Id prob go with elkas if I was going to spend that much. Actually I wouldnt buy new ones if it were me. Ebay always has used works shocks.