I went to my friends house, his brother just had a fish tank, sitting there, empty.
I said WOW, can I borrow it, they said sure. I filled it with water, and went to the store and just got 5 of the cheapest gold fish.
Well gold fish poop alot, and they filter system was very crappy, like a bottom filter. I had no idea what I was doing.
First one died.... I had 4.... then I found another out on the floor, I have no idea WHY he flipped out. then I had 3. I had to carry the big 10 gallon tank to the toliet, and dump it out to clean it totally.. it was a major pain, water is HEAVY..and risky, with 10 gallons of gold fish poopy water.
one day I just dump them all in, flushed it, and was done with them. That was my short 2 months of a fish tank. I was cured.
So sure, do it the cheapest way possible, and see if you stick to it. if you still have them a year later, go more. Maybe look for used stuff, lots of people are getting OUT of fish.
My next pet might be a box turtle. Go on vacation leave him for 2 weeks, hes ok.
You can't just dump your fish straight into the tank. You have to condition the water to handle the bioload from all the fish first.