Living standards for academic/postdocs
The standard of living you'll attain depends massively on where you are and what field you are in (note that my answer assumes tenure, rather than the horribly exploited condition of adjunct professors).  

In the United States, for example, liberal arts professors are typically paid much less well than professors in science and engineering subjects, who are in turn paid much less well than law or medicine instructors.  Location makes a difference too: a big midwestern state university will probably pay less well than Harvard, but Ann Arbor is a lot cheaper to live in than Boston.  In general, though, you should expect that a professor can have a relatively comfortable (if not lavish) lifestyle.

In other countries, academics may have significantly higher or lower relative standards of living.

FYI: For many US public universities, their employees are considered government employees and thus subject to public disclosure of their salaries.  You can thus find the salary distribution of most positions directly yourself if you wish.  For example, searching this database of the University of Illinois system shows that University of Illinois Urbana-Champaign currently has 632 assistant professors: the highest paid make around $200K (at the business school), the lowest paid are visiting professors and clinical professors for whom the bulk of their income is clearly elsewhere, and the vast majority make in the range of $60K - $120K, with humanities at the low end and biomedical sciences at the high end.