Upload & Sell: Off
I buy stuff from all three. I find Amazon is especially useful when I want an order of cheap, miscellaneous accessories --- toss together a handful of lenscaps and filter adapters with some kitchen utensil to make a $25.03 free-shipping order. Often, though, for bigger-ticket items, Adorama and B&H also offer free shipping and the lowest prices on the 'net --- and stock more esoteric, photography-specific thingamabobs not available on Amazon. So yes, I do check Amazon (and other retailers) before buying, but quite often end up at B&H or Adorama after all.