10' X 3' X 2.5', 8' X 4' X 2', 8' X 3' X 3', or 6' X 4' X 3' will all give you around 500 gallons and have a nice big footprint. Glasscages has 500+ gallon glass tanks starting at $2200. Ask your LFS if they have any tanks that big in their catalog and what they'll run you.
A more economical but less aesthetic option is an aquaculture tub with a window, like these from http://www.aquaticeco.com/subcategories/2080/Fiberglass-Tanks-With-Window]Aquatic Eco-Systems[/url]. They have a 523 gallon tank for only $1264.
Look in the DIY section on this site for info on building your own tank; it's still pretty expensive unless you've got a good hookup on materials, but it's easier to customize the tank to the space you have for it. You'll definitely want to build a couple smaller tanks before diving into a 500 gallon monster.
A more economical but less aesthetic option is an aquaculture tub with a window, like these from http://www.aquaticeco.com/subcategories/2080/Fiberglass-Tanks-With-Window]Aquatic Eco-Systems[/url]. They have a 523 gallon tank for only $1264.
Look in the DIY section on this site for info on building your own tank; it's still pretty expensive unless you've got a good hookup on materials, but it's easier to customize the tank to the space you have for it. You'll definitely want to build a couple smaller tanks before diving into a 500 gallon monster.