[designspl]

How much on average would it cost to set up a 50 gallon tank for tropical fish? Just a rough estimate...

[attagirl]

I think that it depends on how many fish you want, the variety you are looking to get and what you really want in the tank. You can do some searches online that will give you a basic price of what you would be looking at.

[matyzyz]

It depends what form do you want for your tank, what kind of rubble you want to use, what kind of plants you want, what equipment like filters and heaters, light and then think about the fishes.
P.S. If it is your first time that you have an aquarium get some cheap fishes.