I agree; I do not like undergravel filtration myself either. Great biological and mechanical filtration are necessities in my book. Aquaclears and Whispers both accomplish this.. I actually am running both at the moment with great results.
I would advise against buying a used filter from an unknown source. I had one that looked fine but upon getting it home (it was packed safely and could not have broken on our drive home I am certain..) I noticed that it had a crack in the plastic and water was leaking out! Just imagine if this happened when no one was around; glad I tested it.
I also advise against overfeeding, especially with goldfish. I like to turn down stronger filters during feeding; this lessens the amount of food they suck up. This is really more of a problem with flake food in my experience.