This is exactly right--by leaving numbers off, they don't set up false expectations. So you call them up and say you want 1 rack, they quote you $100,000. Facebook calls them and says they need 1,000 racks, they're going to sell them for $75,000 due to the scale of the purchase.
Now, if they were selling consumer-targeted items, they'd probably give a quote. But, if you wanted to buy a couple hundred, it would still behoove you to call them up and ask for a deal, because selling 1,000 units to 1 customer is a hell of a lot easier than selling 1,000 units to 1,000 customers.
Kinda like asking $1000 for a glass of water from the man almost dying of thirst but accepting $3 from the man that's jogging and wants a sip.
The problem is I've always seen explanations where pricing is set my the market demand. I'm curious how an economical model would look when there is no market, just this sort of individual negotiations with zero transparency.
Edit: This reminds me of the "how much is your time worth" sales question. Imagine how much a billionaire pays his maid.
As soon as another vendor tries to negotiate with you, there will be a market. Just because it's less convenient for the casual shopper doesn't mean that it's not a market.
What if they are selling an unique product and there is no other vendor? Is there a market when the same product is negotiated at a different price with each customer?
To stretch the analogy, the man dying of thirst hasn't got the resources to find the water himself. The difference in price is determined by the customers knowledge of the market and the product.