On one commercial product I designed a few years ago, I used an SN6505A - a nice chip fit-for-purpose chip designed to match with a Wurth transformer for a medical grade isolated USB 5V DC-DC supply. Normally around $A 1.50 each from TI. None available so the client had to get them from a broker for...
$250 EACH!
Some will say that is capitalism, but I would say it is just opportunistic greed. Thank goodness most of the world does not run like that, else we'd be in a right mess. Oh, I forgot... gas prices.