oddly enough my first set up was a 55g. i was about 12, and let me tell you, at 12 years old, a 55 is frickin HUUUUUUUUUUUGE!
i picked it up at some garage sale for like 10 bucks. it was just sitting on the side of some guys house with 2 cruddy old white ugf trays sitting in the bottom, and i told my dad i wanted it, so he told me to go ask the old man if it was for sale. after a little bargaining for what was essentially "junk" on the side of his house, it came home with me for the low low price of $10 (all the money i had in my pocket. thats how i got him. lol)
picked up a few small air pumps, some air line and stones, and some ridiculous bubble decor (i think i had a pirates chest and a scuba steve.) and if i remember correctly, that was the end of my filtration. not nearly enough for a 55, now that i think about it. lol. es la vida.
every time we went to the mall id hit the pet store for some $1 or less fish. eventually i had a small school of neon tetras, some gouramis, and other small guppy type fish. a small loach thing that lived in the ugf, and a pleco.
... and thats the story of my life. lol