full disclosure: I didn't read every post up to this point, so maybe it has already been brought up.
I have this happen to me all the time, then I steer the conversation to how much they are spending on these "things". I ask about their car payments, etc..... Then I remember "Oh wait, I don't have any of those" and "If I wanted to I could go get money out of the bank right now and go buy it with cash".... Then I suddenly feel a lot better : )
I totally know what you mean though.... In another forum, my signature reads "If you think its tough keeping up with the Joneses, try ignoring them"