If you are looking  for top quality backing tracks, you can visit Bobby’s Backing Tracks or (BBT) . Except the prices, it is a good source  for all types of tunes.

Also for more backing tracks,  Coffee Break Grooves is another place to go for. You will find nice cool jazz stuffs.

Obviously, do not forget Minus One MMO

and of course Hal Leonard

and Jamey Aebersold, my favorite of all times