I was looking at Bandito card game at the store not to long ago and was thinking about the interesting size of the game. It wasn't a standard playing card size, but smaller. It made me think about how one could print smaller card games (physically) at cheaper prices. Folks like The Game Crafter do print on demand, but a deck of standard playing cards with custom art can run around $5 - $6 a piece.
I thought about business cards. What if you ordered a stack of business cards for each unique card in your game? It'd be smaller and more cost effective because, frankly, business card printing is dirt cheap.
If your game had 24 cards in it and you can get 500 business cards printed for around $10, then you'd ultimately have 500 sets at $240. That breaks down to $0.48 per set. Then you could go into a nuanced market with these and buy business card holders, which are also common, in bulk to house the games.
Now to design a game that falls within that constraint!