Jeff Angus talks about situations where a deal seems too good to be true in The Mets: Keep Your Eye Off The Prize
I had a client that had been shopping for a computer system to manage her "traffic" for a long time. The analysis we did said the systems available would not make her operation significantly better than her current kludged manual system with a few automated aids was doing. I came back from a vacation and discovered one of the better vendors had put a deep discount on their candidate (limited time only), and she bought it. The price was right, but the decision wasn't.
Even in our homes, it is easy to see this in play. The grocery store plays exactly to this mentality. Two for one? What a deal! I'd better buy it. Even if I don't need it. Have I saved, or have I wasted money?
While a few bucks isn't a problem for me today, it is never a few bucks in large organizations. This is the reason we need to look at the whole organization when making decisions. If the deal happens to coincide with your overall strategy, then by all means pursue it. But if the deal isn't going to help the organization, why bother.
In the language of Theory of Constraints, as long as you understand your constraints and act to elevate and support those constraints, you should be pretty well off.