Well being new to the aquarium game, I wasn't thinking about all this when I bought the setup and fish. I don't understand why people are confused why somebody would want a small tank - it's not primarily for cost reasons, but for location and preference (looks).
I live in a town house with relatively limited space, and it sits on the upper section of a kitchen bench. It looks nice with the fish at their current size, they swim around lots and have a reasonable amount of room, but I certainly didn't expect the fish to grow all that much.
Here a 10g tank is probably around the AUD$60 mark (~$45 US), just to give you an idea of what things can cost. Naturally they aren't produced in the quantities as over there so the cost has to be higher. I'd love a tank bigger than 30g, I'd even go up to 100g, but there is nowhere to put it.
On a positive note, I did see the
lfs giving somebody credit for some fish when I was there, so there is the possibility I suppose. Are there any fish with a similar look but stay nice and small?
edit: btw, no heater atm. Water sits around 25c (77 degrees fahrenheit i believe), too low? That's the temp now and it's winter here btw.