Outside of the big purchases, home and transportation, it is safe to say if you cannot save for it in a reasonable time you really cannot afford it.

The only time I buy anything on credit is when it is zero percent on the terms and even then if I could buy it outright or save for it quickly.

It just is too easy to get in the trap of credit and reasoning it out is the first indication you have a problem. If its important save for it, if you cannot save for it get credit counseling