New / old stock? I have a supplier called TV SAT in Poland who is pretty reliable. I've had pretty good success with UTSource. But it really depends on what you are looking for. Usually it is a case of looking at reviews and crossing your fingers.

Are they online?

Both are online, yes (I'm UK based and they ship here).

Digikey, Mouser, Newark.

Another comment on this post: "I regularly get fake NXP chips even from the big distributors. Not going to name them here, but it happened at least with the ones starting with A, D and M. ..."

https://news.ycombinator.com/item?id=38559112

Even if they aren't perfect, they are also not trying to defraud anybody. Your odds are much better with them than with other random sources.

So, if these don't meet the standard someone's looking for, buying direct from manufacturer is likely the only way.

Note that in some cases like with TI, this is viable, even if making small orders.