How often is the price of a card not just a function of its strength but also something of an interesting "attribute" of the card? Some examples of the kind of thing I'm thinking of:
You start the game making $3.5 a turn, so $2-$4's are much more a function of 1) openings, 2) utility with +Buys, 3) perception. Well except for early ones where I hadn't worked this out.
Obv. some cards care about their own cost specifically, e.g. Band of Misfits, or have a weird cost thing e.g. Peddler. And all Remodels have built in the possibility of Remodel-ing them. I think those are the main cases - refer to cost of itself, refer to cost of cards in general. Being the bottom of a split pile does have the possibility of making a difference.
Cards try not to be too similar to other cards, but sometimes something similar seems worthwhile, and then it's an issue, it can't be strictly better than another card. This may cause it to do more/less so it can have a different cost. Or kill it.
Sometimes there's a good reason for a card to be cheap or a $5 or expensive - a reactive card wants to be cheap, an early-game card prefers to cost less than $5, a slow (but somehow worthwhile) card wants to cost more. But here the card itself is tweaked to get something that's good at the good cost.
-Border Village could probably work with identical wording and with almost any price on it
Actually it cost $5 at one point, and I improved it by making it at $6. And it can't cost $3 because that's strictly better (as Magic players use the term, not as silly people do) than Village. It certainly varies in value at different costs.
-Poor House is pretty clearly not the weakest kingdom card. Does it really not work at $2? Could other $2s not work at $1? Or is it just that it's a quirky thing to be able to remake copper into something, and you want that to be rare?
Lots of $2's would be a problem at $1, because the pile would empty too quickly - it would be "this game is shorter." Poor House is a terminal that's bad if you aren't going for it.
Poor House itself costs $1 as a gimmick. Sir Martin suggested it.
-Similarly, why Chapel at $2 and not $3? It's probably the strongest $2, and even at $3 everyone would still be able to buy it turn 1.
At $2 it's more available for people choking on Curses (not saying it saves them, but they like being able to get it). At $3 you trade "the 5/2 is extra good" for "the 5/2 is extra bad," which is a wash.
-Would Plunder cost $5 if it were its own pile? Or is part of the "cost" the fact that it's buried under cards half a pile that's hard to drain.
It was $6 initially below Encampment, but being buried felt like it meant it could be $5. I think it would be too good as a straight $5 but don't really know, we didn't test that.