An interesting question.
Personally, I'm not exposed to much advertising. I block banner ads, I don't watch much TV, and in magazines the ads tend to be for games and so on - I already have my own opinions on them, and probably already know the release date if it was something I'm likely to be interested in. Online and physical shopping is very different. Online, I'll virtual window shop. I'm talking clicking and surfing through pages of products on Play-Asia, that sort of thing. I'm much more likely to buy non essential goods online. When physically going shopping, I know what I want and I go and buy it. I try to do this in as efficient manner as possible, but I'll sometimes walk past the CD aisle in the supermarket.
Product loyalty. Absolutely a consideration. If company 'x' has always made a brand of shoes that have done the job perfectly, I'll often not even bother to look at alternatives when replacing them. I've been wearing Doc Martens for nearly 20 years. When my shoes or boots wear out, which is infrequently, I'll go straight to the first place with the best priced Docs. This also goes for electronics. Sony used to make some of the best, I used to always look at Sonys range when shopping for things. Pioneer have always made top quality stuff, so I always check theirs too. This pattern only changes when a previously trusted company
betrays you with something substandard. Sony have betrayed me, recently with a TV with some serious issues (not faulty), now I don't look at Sony TVs. Pioneer have never let me down, I spent £400 recently on one of their DVD player/recorder/HDD units. As ever, it's done the job admirably. I'll look at their products again next time.
Commercial occasions. An expectation of gifts. I buy what other people want me to, them being partner or family. As someone who has a lot of 'stuff', I've come to the realisation that I don't want random things given to me, and neither do I give them. I ask people what they want for these occasions. While I am a consumer, rampant consumerism annoys me.
Changes in society. If everyone else gets a Plasma TV, I won't. I think this affects the Joneses more than someone with a clue. However, there's an interesting recent example of how social situations can drive consumer behaviour, even in people who are otherwise immune from that kind of buying. The Xbox. You get Live, meet people, make friends. Then - the new one comes out. You want to keep playing games with your friends, and end up buying a 360 early rather than waiting, because they did. I did.
Technological influences - not sure what to make of that point - maybe that's my answer to it?

If I have a need for some new tech, I'll buy it. If the old tech still does the job, I'll keep that instead. I still own late 70s and early 80s hifi kit, it still sounds brilliant. I don't need a wireless network, wireless controllers, or a wireless doorbell - needless technology for the sake of it in most cases.
Fashion doesn't affect me - even slightly. I buy what I need and like! I only have a mobile phone because my work gave me one. I buy clothes only when the old ones are beyond repair, and I just go and buy something that I like. Frequently if I can get an identical replacement that isn't worn out, I'll just get that. I've been wearing the same overshirt for 7 years. It is mostly falling apart and full of holes, but it still functions. When it's actually falling apart, then I'll replace it - probably with the most similar thing I can find. I repaired one of my pairs of jeans last week. It's not that I can't afford these things, it's just that I see no sense in replacing them. I always repair anything I can before replacing it. This bit went off topic.
Cost of products - I tend to buy what I want, I'll shop around for the best price but it rarely has an effect on exactly what I'm getting. As with someone else above - I get a good income, but I'm unable to afford a house because prices are insane here. I should save the money, but I waste it instead on cars. I'll probably hit an early grave anyway, so it matters little if I've nothing left when I die before retirement - there are no children.
Aside from the points you raised, there are other reasons people will buy things. Whether this makes them a contemporary consumer or not, I have no idea - still havent quite got my head around the definition, so instead I've been covering /why/ I buy things. I'll let you decide if I'm contemporary or not
People will buy things when they are bored. Pure and simple - this happens a lot. I do it. Lots of people do it. Something new to bring interest to an otherwise dull life. People will also buy to cheer themselves up - retail therapy. Again - I do this, other people do this. These are usually more impulse purchases, or the bringing forward of something you'd buy later. "I'm treating myself". If you're a collector, you might extend your collection.
Of course, the other reason people buy things? They buy things when they need them

Food, fuel, tools - necessities. There's a sublevel to this that I /know/ I'm guilty of, I'll frequently buy something slightly better than what I really needed. The slightly better brand of food, the better more capable powerdrill (a recent example), the car with the bigger engine. I do this, because I can, and partially it makes me feel different for a moment, above the people buying the basic car without the power steering. I think everyone does this in their own way - wanting if only in some small way to have something better than everyone else, or better than they generally can afford. We aren't all bank managers, but we like to buy things that make us feel like we are.
There you go - a mixture of practical, logical, and psychological. I don't really mind buying things I shouldn't for irrational reasons, as long as those reasons are not ones I despise: following fashion or advertising. I want to buy things because *I* want to, to feed my own practical, selfish or nonsensical desires - not because other people want me to.