my favourites here in the US are glasscages.com
they have a huge variety, are very reasonable and will modify for a reasonable charge
they come to most major expos
I call them about a month ahead, if I want a modification
the most expensive tank I got from them was a 4'x2'x17"
I had them put in sliding doors (modification)
it came to $180.- total
I don't have the time to build tanks
I do build racks for the tanks
they're a bit rustic
I'm gonna redo this one after we move
I was so entranced with the sweeping grain on the center board, that I didn't realize how warped it was
also - I want to fit another tank or two