Echoing the message from SPCA - Pets are for life.
Please consider the after purchase husbandry work before taking the plunge. Fresh water fish-only tanks are less demanding than marine ones.
For more information on marine tank husbandry, read up on our forum's sections on setting up of marine tanks.
After careful considerations if you still want to proceed, please do feel free to ask questions in this forum. But please do a search first as your question might have already been asnwered previously. Thanks and Happy New Year.