from the equipment list, it seems like the quotations you are getting are not from shops specializing in marine setups. would advise you to go to shops specialising in marine setups. even if you don't engage them, you will know from the quotation what you are missing. marine setups are a bit different from freshwater setups. the supporting wood structure have to support the heavier saltwater and rocks and it has to be resistant to corrosive saltwater too. imagine the weight your tank is supporting and the mess it will create if it gives way one day. i wouldn't scrimp on the tank.