Sorry, I missed that you were comparing five Hubbles to five resupply missions, not to one. But I'm not sure you would have been able to get five Hubbles for an

Sorry, I missed that you were comparing five Hubbles to five resupply missions, not to one. But I'm not sure you would have been able to get five Hubbles for an average of ~$500m each either. (OTOH, all this is just considering what the best option for Hubble was, taking the existence of the Shuttle as a given. Justifying the existence of the Shuttle partly in terms of the Hubble would be more difficult: that $450m-a-flight figure doesn't seem to include development costs...)