Honestly? Looooveee
Amazon.com -- they typically have what I need. And I'll just spend over $25 to get free shipping and stock up on things I need. Always get awesome prices and great return policy, etc.
Food/treats/chews/etc, if ordered online, are from
MrChewy. Super fast shipping, great service, great selection and GREAT prices.
I have other favorites as far as collars and such go.
Ella's Lead and
Paco Collars are my favorite place to shop around for nice leather collars. I like
EuroDogDesigns because they sell a lot of harnesses, jackets, etc, only usually available in Europe. Dog tags I get from
Fetching Tags.
Oh and
Etsy is awesome for almost anything -- lots of great sellers on there.
BaxterBoo is awesome too with a great selection, heard great things, never personally ordered from them though.