I really liked the recent New York Times Motherlode blog post, A Stay-at-Home Parent is Not a 'Luxury'. I have sometimes been irritated when I've been told this about our life, but haven't been able to put into words exactly why it bothers me, and the author does a pretty good job summing it up.
To some extent, of course, my staying home IS a luxury - there are many families where two incomes are required simply to provide for basic needs. But in comparison to most middle class families, it's simply a matter of priorities. We don't go on nice vacations. We don't have game systems or cable. Our kids don't do things like music or tumbling classes or immersion preschools. Why are those things not considered luxuries?
My staying home means less income, and it also means less spending on things that are just for fun. We live comfortably, for sure, but I don't feel as free to spend (especially on myself) as I did when we had two incomes, and we weigh our large purchases a lot more carefully than we did in the past. If my staying home is a luxury, it's because we gave up other luxuries that are more often considered necessities - cable and takeout and enrichment classes and weekends away. It's all relative.