Buying used can definitely be daunting. The 55g acrylic tank you linked also has power compact lighting in the canopy, which you'd likely want to replace with either T5s or LEDs. Power compact lighting is older technology and while I'm sure you can still get replacement bulbs you'd likely be better off switching (I echo the advice of changing the bulbs in a used system anyway).
The Bioballs you would definitely not want to use for a reef tank.
As for the Nuvo Fusion tanks.... Yes you would still need a heater, sump, etc. There are some tricks to save money you can use though. A sump CAN be a fancy custom built endeavor, or it can be a cheap 20g glass tank with some glass baffles siliconed in. Both will work equally fine. Heaters you can generally get away with something like an Eheim Jager or other well known brand.
Pumps and flow are one of the more pricey parts of any tank, but again there are options. For in tank flow you can go really fancy and expensive for an Ecotech Vortech or Tunze Stream type device, or you can get one of the Jebao brand wavermaker pumps which get good reviews and cost less. By all means not equivalent but a reasonable starting point.
Lights are going to be another pricey point. I'm so mixed on that. I did DIY LEDs from RapidLEDs for my tank, and when I add up all the time and effort to build them and get them running I probably should have just bought a premade light like a Kessil. The good thing is that with LEDs you're not going to have to replace them every 8-12 months like halides or T5 lights. So although they may be a higher up front cost you'll save on bulb replacements.
Other things to consider for a setup:
- RO/DI system - can't beat the 5 stage with RO/DI from a place like Bulk Reef Supply
- Auto top off - you CAN get away without it and manually top off, but I find salty tanks evaporate loads of water. Doesn't have to be a tunze osmolator, but can be a cheaper one and it'll work equally well.