If you know the dimension and designs of what you want you can order from alantic glass which provides really cheap prices for tank only. From my memory, they do only tank but not cabinet.
But if you are not sure of anything, you may look for vincent (aquarium artist) or CR aquarium for a one stop solution.
Personally have used both of them for my aquarium i will have to say vincent provide very good services and never shy of giving advise if you ask.
As for CR, i would advise you to think of your own design as they are more specialise in fresh water rather than marine tanks. But the quality of their build is still very good.