yeah, I got a 64t alloy for $10US on ebay just the other week. Still, the postage should be only about $10US. $40us all up is about $46ish here in the real world so in fact that price for an alloy rear isn't over the top
not sure what 64t is like as I'm yet to run it but I've a choice of fronts to compensate a little.
oops..I just reread your post..he wants $30 postage!! Bloody Nora! I'd email and ask if this is correct