Some aquarists believe a QT is a waste of time and money, thinking that fish can stave off disease, parasites or infections on their own. Most experienced aquarists would disagree, having seen entire aquarium systems wiped out by the introduction of a new critter which brought a disease with it. You can decide for yourself if a QT is worth it.
More: Cheap, Easy DIY Quarantine Tanks. QT's don't need to be fancy or cost a lot of money, they just need to work.
More: DIY Aquariums are terrific Quarantine Tanks. Inexpensive, easy to build and they can be designed to any size you want.