Just fine, RAW, due to how component pouches and spellcasting foci work
First, don't take the specific material components for each spell too seriously; they are hold-overs from the early days of D&D, and are mostly there for flavor. (They are also, more often than not, jokes. Message is a copper wire...a phone line, get it? And don't get me started on the legumes for Gust of Wind.)
Mechanically, in 5th edition, they have been trumped by two classes of objects: the Component Pouch, and Spellcasting Focus (whether Arcane, Druidic, or Holy Symbol).
The Component Pouch basically lets you ignore those material components, as per the PHB Equipment. (Bolding added by me.)
A component pouch is a small, watertight leather belt pouch that has compartments to hold all the material components and other special items you need to cast your spells, except for those components that have a specific cost (as indicated in a spell's description).
The Spellcasting Focus mechanically works the same way as per the PHB Spellcasting.
A character can use a component pouch or a spellcasting focus (found in chapter 5, “Equipment”) in place of the components specified for a spell.
Jeremy Crawford, the only person on the Wizards payroll who is allowed to make official public rule clarifications, has backed that up via Twitter.
If you're using a spellcasting focus or a component pouch, free components are abstracted away.
So, since the component for Banishment doesn't list a gold piece value, it's covered.
RAW, you only need to worry about having those material components if you are without a Component Pouch or Spellcasting Focus. Since every 'full' casting class is given a focus or component pouch at character creation, the intent is they're abstracted away by default. So, the only time you'd really have to worry about it in RAW is if you have been stripped of all your equipment.
I can think of one edge case; a Good-aligned spellcaster with a Focus wanting to Banish a Good-aligned extra-planar creature. Then, depending on the flavor of the campaign, I could see a DM ruling that you'd need to obtain something distasteful to make it work, since the holy symbol or crystal or whatever probably isn't.