I pretty much make a habit of impulse buying when it comes to things that cost less than, maybe, $3. I'll often have a limit of $5 or so, and just plan to pick up whatever I happen to see. Actually, I'll set the limit at $4 and "allow for a dollar margin of error". LOL
With larger purchases I don't impulse buy. My purchase are all very much a matter of being premeditated. I don't so much compare prices, as I compare what the item will offer me in terms of other things in life (besides just its presence among my possessions). I lean toward stuff that offers me things like being able to offer guests/family members something, a little more freedom or time, more convenience, etc. The purchase also has to be at a time when I've allowed for making such purchases.
The excitement or novelty doesn't pass with those larger purchases. I'm usually pretty darned thrilled with what I've decided to buy. As for those little impulse purchases of $2 "junky stuff" - the novelty wears off almost as soon as the stuff is out of the bag. LOL