Acrylic Tank Manufacturers is a well known aquarium maker. Their "average" contract is $30,000+++++. They create things in public aquariums, zoos and such.
You can purchase glass or acrylic aquariums from all-glass or glasscages.com
As with any tank you have to figure out what your floor can support. Also large aquariums require thicker glass/acrylic width. You are talking about a 240-300 gal aquarium so your glass width will be 3/4 to 1 inch thick. Aquarium of that size would run well over 1000 dollars, another 1000 dollars in filters and media, probably a 20-50/mo monthly electric bill just for the tank (3 times more if you heat it).
You would also need stands, lights, ship and deliver tank to you. In other words you are running into probably a 3000 dollar operation for a 300 gal tank.
Some people cheat by installing 1 pane of glass and build up 3 walls of tank, insulate etc etc. That probably saves about 50% of the cost but is a lot more difficult to do.
If you want a 1000 gallon tank fresh water... expect to spend about $10,000.
Trust me it is a lot cheaper to buy a bunch of smaller tanks and put them next to each other than it is to buy 1 big one.
Just for reference. 20 50 gallon tanks cost about $2700 where as 1 1000 gallon tank costs about $6000.
Another really important thing to keep in mind is that most people put their tanks against the wall or build them into walls so most people want to see long tanks. With long tanks you do not necessarily have to get large volume tanks. My old buddy had a 240 gallon tank mounted in wall between kitchen and living room. It was HUUUUGE. I currently have a 55gal and a 37 gal but will custom build 4 75 gallon tanks into build up wall or 1 100 gallon skinny tall wide tank ... have not made up my mind yet.
My next house is getting a custom build ATM ordered acrylic tank probably 1000 gallon or so build in middle of house and have entire house build around that tank.
