Interesting question. I could definitely see scanning bar codes out of magazines being a fad, but I could not see it being a lasting trend. It is a good idea in theory, being able to instantly find out if you can get a better deal on an item from another place of business. But I see two problems with this.
First is that not everyone is willing to travel to another store to get the best deal on each individual products. In other words, some people like the one-stop shopping experience and find it more convenient to buy all of the products they are looking for in one rather than travel and save the few dollars. I know that they could be finding better prices online, but not everyone is willing to send their credit card info over the internet and then wait for delivery.
Second, you would either need a lot of bar code magazines, or a device with a large memory unit to be able to look up a variety of bar-codes and compare the prices to many competitors. This means buying another expensive piece of electronics, The i-compare maybe? And on top of that, prices change so fast you would need to update your system all the time.
Good idea, but it seems like a hassle.