Synonyms for Premium (same or very similar meaning)
WordNet sense 1 (a fee charged for exchanging currencies):
agiotage, agio, exchange premiumWordNet sense 2 (payment for insurance):
insurance premiumWordNet sense 3 (payment or reward (especially from a government) for acts such as catching criminals or killing predatory animals or enlisting in the military):
bountyWordNet sense 4 (of high or superior quality or performance):
superiorFrom the ODE community, based on WordNetadd/edit