I think is highly unlikely that you will get an "insider" response right here. Your main real question is:
"Is there any public information on how significant websites price their particular cards?"
And a simple solution would-be: No. Wizards associated with the expense doesn't set costs on ANY card, everything precipitates to exactly how much individuals pay, supply and need. Whenever a unique ready releases, I would say there is some sort of standard rates with respect to the card rareness. For this reason, very near to the launch, the thing is that many Planeswalkers expense around $20, and then those with a top need head to around $40-$50 pretty rapidly. It's over time and employ associated with cards, need or overall performance various decks, that prices settle at some point. For a while at least. It is possible to predict, like, that fetchlands that are now in standard will see their prices go through the roofing when Khans rotates from the structure.
For automation, TCG has a cost aggregator (believe as to how pricegrabber.com works), plus they have information from different sources. They're not really pricing everything, simply showing you lowest prices. The majority of these records (think about solutions offering them) are community (for a cost). So, officially, you are able to study the behavior on price of different cards and variety of "predict" rates of similar, future cards, with a few margin of error. At the end, the cost of a card relies on perception for the price it can have on a given deck. And also this is quite challenging placed on signal.