If someone buys a domain name specifically to resell it, then you would think they would have a price in mind.
I recently came across a name I want, and when you visit the site it says this name is for sale. They even have a form on the page to request the price. But they won't respond! They have a telephone number to call, but then their automated system puts you on terminal hold.
This is not an unsolicited request... they stated want to sell the name. But I guess they don't want to quote a price because they're afraid they'll undersell it. I can understand not wanting to name a price when the inquiry is unsolicited, but for pete's sake, if you want to make a business out of selling domains, then come up with a price when it's put on the market!
Maybe they are just trying to gauge interest to later determine the asking price?
I know I have listed some of my names at very low "minimum offer" prices and no asking price to see how many offers I would receive. It's an easy way to tell how interested the market is in the name. Of course, lots of interest doesn't mean they will pay a high price but it does help.