Do you have any concept of the type of fish you are interested in, e.g. large fish, small fish, algae eaters, piscivores, etc.? Different types of fish have different types of care and feeding requirements. You have to provide for your charges.
As well, you have to consider compatibility amongst your charges. You don't want to spend hundreds and hundreds of dollars on exquisite small fish from around the world and then have a $30 lionfish scarf them all down in the first week.
Dave.M