speaking for myself & i guess when i say someone looks "expensive", i mean that their look is beyond otherworldly gorgeous.. That they possess this aura of grace, poise & are soo captivatingly BREATHTAKING that they're naturally suited to sell the most richest, sumptuously items & can make the cheapest, shabbiest of clothes look high end & expensive

. It's pretty much inconceivable to call them mere mortals cuz mere mortals don't look like this

...
ex-
Shanina Shaik & Anais Mali
source: modellove.co.uk
there are a bunch more but those examples are off the top of my head so i hope this help somewhat
Shanina does not have an expensive face...
Expensive models are more suited to runway and high-end campaigns. Its opposite, "cheap" describes more commercial models who do work for brands like Guess, DKNY, Gap, etc. But there are also high end commercial models who are equally at home on runways. They bridge the gap between the two worlds and usually go on to become supermodels. These models have faces that are "universally" beautiful without being trite.
Edita is a great example of such a model.
What's the difference in look between an expensive and cheap face in the modeling world?
Expensive features tend to be more spare, refined and asexual. Sometimes they can border on plain or androgynous. Thinner lips, bigger noses, higher cheekbones, weirder coloring.
Cheap faces are sometimes more traditionally pretty but in an obvious or overtly sexual way: smaller, more upturned noses, fuller lips, rounder faces and less prominent bone structure.
Another way of being cheap is just being bland. I'd argue that Kendell Jenner has a cheap face and would be withering on some direct board if it weren't for her family connections.
That said, there are traditionally beautiful faces that are also expensive and feminine...they're just rare. See my Edita example above. Doutzen Kroes is another face that is traditionally beautiful but more expensive than the sum of its parts.
But because her features are so sexy they can look cheap if she's not styled properly:
It's hard for me to explain why she usually manages to look expensive. I think if a face is universally beautiful and striking enough (like one in ten million) it usually looks expensive, no matter how conventional its individual parts. Somebody like Kendall is simply not pretty or distinctive enough to qualify as expensive.