To buy or not to buy?

Our text suggests that their are four factors that influence consumers on whether or not to buy a product. These include social factors, individual factors, cultural factors, and psychological factors. The factors that I believe influence me to purchase a product or service the most would be psychological. My beliefs, attitudes, and perception of the potential purchase will usually determine my motivation to buy the product or service. The other factors do add some influence as well but ultimately it comes down to whether or not I perceive it as the right option. I am not saying, however, that I  have never made a purchase based on individual factors (gender, age and family life cycle stage, or personality) or social factors (reference groups or opinion leaders). Different product or services call for different consumer decision-making process factors. 

What was your last purchase, and what were some influencing factors that helped you make the decision?