I'm only a few hours in, but can anyone let me know if I'm missing an obvious way to buy/craft bombs? None of the merchants I've encountered near White Orchard seem to sell them or the two components necessary for them. Am I just being obtuse?

You have to craft them it seems. I just eventually had the materials at some point after playing for a while. So can't help you on specifics. :(

You start out already knowing a couple of formulas in your alchemy tab. It does take awhile to gather the components for them though. Your best bet is just to steal the hell out of everything that isn't nailed down and hope you come across some. You might get some if it from deconstructing junk at the blacksmith too. It's worth it to invest the time - the bomb radius is a lot bigger than in Witcher 2 and helps with groups of mobs. You also need a bomb to destroy the monster nests you come across.

The good news is once you craft them, they auto-refill on meditation as long as you've got the materials.

You need to craft them. And need to find the components out in the world or on merchants. You aren't missing anything obvious per se.

It's just not super easy, because now crafting oils/potions/bombs creates a persistent item stack that replenishes when you meditate using just alcohol.