Or, you could just buy from your LBS when you need them. I've gotten Pro Race and Conti 3000's at LBS's for just a couple of bucks more than the online guys, and like to keep them in business too...as long as the price diff isn't too great!! You can hunt for bargains, but seems these top line tires don't go on sale very often....they stay in demand.
Anyway, agree with Capwater that good tires are worth getting.