Did you get that quote from Tyre Power? I remember getting around the same numbers when I called lol.
$500 for shipping is definitely not right, they quoted me $270 shipping for 1 set (regardless of whether 18" or 19" they gave me the same price). I am 100% sure because I just bought a set last week and it's on the way to Brissy now.
You should try and email Larry who was very helpful:
larry@tirerack.com