Firstly, his first paragraph is an example, whose details don't matter. It's the third paragraph that is most important.
Secondly, if you initially have no need for something and wouldn't have felt any need for it if no one had pestered you about buying it, then 'I did not want it' is an entirely acute way of phrasing the way you felt about it, before you were brainwashed into buying it.
Thirdly, your use of 'want' and his use of 'want' may be different. In 'ye olde English', "having want of something" means: needing it. For Russell, want and need may be more synonymous than for you. You could read "buying what they don't want" as "buying something they don't have want for". I'm not sure this is the case, but having read other writings of Russell, I am sure that his English and our English are different creatures, with some differences that can cause strange misinterpretations.
Fourthly, and perhaps most importantly, there is a world of difference between wanting something because you think you need it and wanting something because you have been assaulted with so much glorious reports on the goodness of 'it', that not having 'it' leaves you with a nagging feeling that you should want it.
As an example of the last bit: I consider a car a utility. I have an ugly and scratched car, but it serves me very well and I like it this way. However, that doesn't mean that I can avoid conversations about shiny Ferrari's or someone's brand new SUV and I can't avoid being given the feeling that I should care about my car. I constantly have to stand up to the cultural indoctrination and reconvince myself that what I'm doing is perfectly fine. I don't need a shiny car, but I often feel like I want one. That is what Russell is talking about and that is still something that is very wrong about our society.