That's kinda a crap shoot. Some physical titles you will be able to find very cheap. Others you'll just have to settle for digital download, because the physical release didn't get a lot of printed copies, so the prices have inflated to sometimes astronomical amounts. Any officially licensed Nintendo game will also rarely go down in price. Nintendo never makes adjustments on those prices and keeps them inflated which in turn keeps the used copies very expensive. GameStop will sometimes have cheap copies of used games, but it's pretty rare nowadays. I mostly just order new stuff off of Amazon or Walmart and settle for digital on the older stuff, because of how inflated the prices get.