There are basically 3 types of spells, when it comes to components:
1. Spells without any materials required. These are easy and obviously don't need to be tracked.
2. Spells with components that do not specify a cost or value for the components. These do not need to be tracked, however the player does need to have a component pouch or an arcane focus to cover the cost (as well as the free hand to use either). It's worth noting that the component pouch never really needs to be "refilled" or anything, so contents of the pouch don't really matter.
3. Spells with components that *do* specify a cost or value for the components. These *do* need to be tracked, which means your wizard will probably have lots of random high-value items in his robes or pouches (gems, carvings, etc) in addition to his normal arcane focus or component pouch. You also need to track when certain spells destroy the component as part of the casting, and which ones simply require a valuable item to be manipulated.
Ignoring these details won't break the game any, but there's really no reason for them not to be able to afford the components pretty quickly. I also wouldn't recommend ignoring components for 1st level spells, because that's the whole purpose of cantrips. 1st level spells *should* be considered useful and special, unlike older additions where they were considered baseline.
