To my knowledge, stores actually encourage discounts on more expensive things. It's their way of getting you to buy more expensive stuff.
For instance, some stores will send you a coupon for 10% (or 20%) off on an item as long as the item is over $50 or something.
I once got a coupon for $5 off any EA game. When I went online to redeem it on an old game (released months or years ago), it didn't work. When I checked the fine print, I realized it would only work if the game was priced $50 or more. No, that doesn't include games priced at $49.99!!! Well, their games were priced at $9.99, $19.99, $29.99, $39.99, $49.99, and $59.99. That would mean I have to spend $60 to save $5 when I could get the same game for $50 at Best Buy or Gamestop. :roll: