Value of money - Rich vs Poor

I was looking through a Family Dollar today and wondering about the difference between people for whom that's the grocery store, and people who can't be bothered to go to a place like that for a few cheap items and then to a supermarket for the rest, even if they pay a few dollars more. It got me thinking about the mechanics of the phenomenon from a game design point of view: why would anyone pay more for the same item? Why does your definition of frivolous change depending on how much money you have?

The reason is that people's time and effort have intrinsic value. I could go to Family Dollar and get 3 or 4 items for about $1 cheaper than at Safeway, but they don't have all the stuff I want, and I'd have to go out of my way to save that money. If I couldn't afford to spend the extra couple of dollars to buy everything at Safeway, then maybe I'd spend the time and energy (resources I did have) in order to save the resource I didn't have.

So how could this be applied to a board game? This is what I came up with so far...

Suppose in a game, each player gets a set number of action points each turn, the same number all game. Players also get some income each turn, and at the beginning of the game that income is small. Over the course of the game, players' incomes will grow such that later in the game they are making a significant amount more than at the beginning. In this game there's a deck of "stuff" that you can purchase by going to a store, and there are 3 stores characterized as follows:

Lower Class store: spend 1 action point to draw 1 card from the "stuff" deck, and then pay $1 per card you want to keep.

Middle Class store: spend 1 action point to draw 2 cards from the "stuff" deck, and then pay $2 per card you want to keep.

Upper Class store: spend 1 action point to draw 3 cards from the "stuff" deck, and then pay $3 per card you want to keep.

Thus as you get richer, you may be willing to pay more money for the same items if you can do so more action efficiently. In effect, you're buying more actions with that extra money you're spending, and in most games, extra actions is a good thing. Of course players would spend those actions (and "stuff") on things that get them points or increase their income, or whatever else the game does.