Over the last 5 years or so, have purchased well over 20 scopes, most of which was from some site selling optics on the internet. Mind you, most of mine cost me in $100 to $150 price range and most are brands generally bad mouthed by folks. However, they've worked quite well for my target shooting needs with mostly centerfire rifles.
Anyway, Natchez Shooters Supply, Grafs and Sons, Optics Planet, Amazon, Midway have been my main sources, with Natchez being the prime one to buy from. Only bad thing about Natchez is their shipping cost runs higher than most others, but dispite that, whenever I've compared prices on a particular model/brand scope, still saved money buying from Natchez.