chadjenofsky: It's a marketing tactic. Just like $89.99 looks cheaper than $90.00, bigger percentages in sales look better than smaller percentages--or even if the sale price of an item in one store turns out to be more expensive than the same item NOT on sale in another store. People are given that emotional satisfaction of finding a "bargain".
Emob78: And companies know that. After working at Walmart for years, I finally learned the lesson of selling two $3.50 products with a 'two for $7' sign.
Magic tricks. They don't always involve cards or pulling rabbits out of hats.
Social psychologists and other people in social behavior-related fields have studied consumers' emotional and psychological behavior for so many years--motivated more than just the "science discovery" factor--have found how to formulate the best techniques to dissuade people from saving their money.
As for the OP, by asking the question "Am I cheap?", it implies a negative connotation to being someone who is "cheap". I would say this was caused by society's aversion due to an injected belief system put in place by those who want us to spend (or at least aided by targeted marketing to reaffirm this negative connotation.)
dal4fsu should consider his buying strategies to be intelligent. By going against the grain of automatically buying when things are "on sale" takes more willpower than one might think… especially based on the years and money spent training us all to be consumerist bitches.
Now, if you'll all excuse me, I have about 30 minutes before the sale ends on "Starpoint Gemini 2" and Adam Smith's Invisible Hand has put me in a chokehold and is literally forcing me to buy this limited-time offer now! ;-P