I find myself doing this all the time.
Tank of gas= 1 SM58
Groceries= 2 SM58
Parking pass at school= 3 SM58
Rent= 7 SM58
I'm worried.
I often compare tanks of gas to family things like kids shoes, kids play stations, private school uniforms, our own entertainment budget, etc
Also I compare larger audio items to things like property taxes, vehicles, insurance, what else I could have spent the money on if I hadn't done audio, etc.
20 years ago though, I remember comparing the price of brand new Cds to tanks of gas. Today, I compare tanks of gas with small audio items. Says something about the price of gas, and also about the price of audio items over time. CDs not so much.
On a different note, while in the music store recently I walked past the projector that's supposed to mimic water ripples in a body of water. For just a moment, I thought "this is the Stargate, and I am about to enter it".
Another quirky thing I sometimes do when away from home is to inadvertently look for the review button on a TV remote - which by the way isn't connected to a Tivo or DVR. I do that a lot.