From google searching "large fish tanks", brand new 120x36x48 900g for US.$8399. Their website has new, used, etc tanks. Lots of 900+ gallon tanks but they are pricey. I see things on Craigslist once in a while and they are sometimes a little better priced. If you are serious you can always check with a LFS as they would know who would have them. Another thing you can do is talk to someone at an aquarium if there is one in your area. Sometimes they have ones that they need to get rid of or at least know who to get them from.