Setup a saltwater tank is expensive for equipment as start like base/live rock, sand/live sand and cycle your saltwater tank, a healthy and do it right for fresh new saltwater aquarium would take up to 6 months to get thing stable. Also, you can't just buy saltwater fish and add them in your tank same time cause the bio load spike will kill them or stress them out and disease will show up on stress fish (add 1 fish every 4 weeks). Another important thing: you must have a quarantine tank for your saltwater live stock, you don't want a carry disease one kill entire your tank and saltwater species price is not cheap especially on nice colorful corals.