When do you "turn-on" your financial brain?

There are times when we just reach into our wallet or purse, pull out the cash and pay for the item(s) we want and then there are times when as we are getting ready to purchase, we stop and think and think and think before laying down the cash.

That "thinking" is what I call "turning-on my financial brain". At what dollar amount do I start having thoughts about buying or not buying?

Here's the process that I go through most of the time and to set this up, you need to know that In my biweekly budget, I get $20 of blow cash every two weeks. (Don't laugh at the amount.)

1. How much of my blow cash do I have left in my wallet right now?
2. Is there anything coming up that I know about between this purchase and my next blow cash installment?
3. Am I wanting to buy this item because I perceive this as a good deal or is it something I really want? A good example of this for me is the Power Bars at Big Lots. Most of the time I'm thinking to myself "This is a great deal. I better pick some up before they are all gone." I've got lots of Power Bars at home already.
4. What would I or could I do with the cash if I don't buy that item?

After going through that thought process, sometimes I buy and sometimes I don't. Sometimes I even feel guilty over my decision. (I wish I could get over that feeling. That's another blog post topic.)

Anyway, that's kind of my story. As your thinking about this, share your thoughts with me. When does your financial brain turn on?