I've purchased a few pairs from Solstice, and I remember getting a discount - somewhere between 10-20%, however, I don't know if they always do this. You can call and find out though!!
my optician has them slightly less expensive than retail and he charges no tax for some rason.
I have purchased from Solstice Sunglass Boutique as well. They will not give you any type of discount on Chanel sunglasses. It is by the request of the manufacturer. Sometimes they have promos going on where you get X amount of every X amount you spend- around 20% but it always excludes Chanel.
I wait for the department stores to throw their annual Friends and Family events and take advantage of the savings. Bloomingdales recently had their event (not sure if it is still ongoing) and I bought a pair of Chanel sunglasses for 20% off retail. You can give my sales associate a call at 415-856-5405. Her name is Whitney and she's located in San Francisco.