I agree with LilyBLily that quite a few of the thrifty things I've heard people do are more relating to being genuinely hard up for cash - like cutting one laddered leg off two pairs of tights so you get one complete pair, or reusing tea bags (which has come up already), or buying up shampoos, etc, on discount, going to cash-and-carry for a year's worth of toilet rolls. That kind of thing.
I did once work with someone who was very well off and still drove a 20 year old car, and not the classic type - think very battered, long past its best. I genuinely don't think he saw any need to change it - it still worked. (This reminds me so much of my dad - it still works!)
That said, something that might fit, and which I think is quite funny - an anecdote many years ago from a former work colleague: round at someone's house for dinner, the hostess brings out coffee after the dinner in a big cafetiere, waits for it to brew, depresses the plunger, and then, when coffee is poured, announces to the room that the coffee is in fact instant ...