You can get 10g tanks at Petco for $10. These are nice because they're easier to mount pumps in and you can see your fish. With 10g, you can probably also quarantine slightly larger fish that need more space than a 5g bucket can hold comfortably.
This is what I have:
- 8g tank (a spare I got a long time ago)
- Penguin BioWheel filter
- Tetra whisper air pump + a bunch of airstones
- 75watt heater
- Eggcrate to cover the top
- A handful of MarinePure ceramic spheres or reef rubble in my current tank's sump that I'll use in the QT.
I'll start running my QT tank at least a week before getting new fish, and seed it with some reef rubble / marine pure spheres. I'll also dump a small bottle of BioSpira to get things going.
Then QT the fish for 2 weeks, dosing Prazipro and using Seachem fusion + metroplex + garlic guard for food.
If you want to also treat for Ich, you can also just do the TTM method, which you probably won't need all the bio stuff since you'll be changing out to new water every 3 days. Just keep an eye on the ammonia and use Seachem Prime when needed. Usually feed on the second or third day of each TTM cycle and you won't really have any ammonia.