"New" doesn't always mean it should cost what it would or should sell for. The example of limited run pressings for current bands is a similar analogy to what you are describing. 500 copies are pressed, only 50 of them come on the elusive orange cream vinyl, with various other colours in varying degrees of quantity. They all were available for $30 from the label, but upon making their way to ebay, suddenly the orange cream version is commanding upwards of $150, and the record was only released 2 months ago. It's all supply and demand, and these values have a way of working themselves out. If there really were tons of them out there, they probably would sell for 15-20 dollars (to address your example).
But are they new releases? Or are they reissues of vintage records?
The limited issue MONIKER is as old as the hills. It's a ploy that works often just as the scenario you described.
I have never got the reissue record market with some exceptions.
And my main complaint is the ridiculous prices.
To each his own but I would rather dig for originals.
I have purchased reissues twice in the last two years because they were impossible to get any other way, (Without spending $$$) and I had returns, and at the time thought they were the best re-purchase.