Context means "the set of facts or circumstances that surround a situation or event". "Put it in context" here means although the consumerist culture is very popular, you should say I cannot afford it. And you should combine with the actual situation when saying this. It's not only a "can afford it“ or "cannot afford it" question. You should also consider other aspects, like whether you really need it, whether it's worth its price, etc. I believe you could find answers in the original article.