Thankfully, I’ve only passing experience with some of these things, but in my limited and humble experience, John Scalzi nails it:
Being poor is knowing exactly how much everything costs.
Being poor is getting angry at your kids for asking for all the crap they see on TV.
Being poor is having to keep buying $800 cars because they’re what you can afford, and then having the cars break down on you, because there’s not an $800 car in America that’s worth a damn.
Being poor is hoping the toothache goes away.
There’s more. Please go read it. (Then email it to the next person who blames Katrina’s victims for not leaving.)