I seriously love https://www.musiciansfriend.com. Let me tell you why! Whenever I need something for my violin or a gift for someone in my family who is musically inclined I always check Musician's Friend first. I find that many of the items on the site are cheaper than I can get locally, but Musician's Friend also has a low price guarantee.
Now I love the site even more because there's the "Stupid Deal of the Day" where you can get 1 item at a majorly discounted price each day. Plus there are also coupon codes available through retailmenot.com, and the average retailmenot user saves about $24! How awesome is that?