You asked.....so I am going to throw out my opinion. Personally I think you may be asking the wrong question. My recommendation is to pick the fish that interests you the most. Research it. Make sure it is the fish you want for the long haul. Understand the care requirements which include the needed tank size. Plan accordingly, save up if needed for a new tank or scour craigslist until you are able to afford the needed tank size. Consider everything, heaters, filtration, chemicals, water changing systems lightning etc and then plan the financial aspect from there.
Basically what I am saying is pick the fish that floats your boat and make your plans according to that.