I've stolen things of more monitary value... but the best theft I would say was probably a $40 microSD card... But I didn't steal it for the card, I took it for what was on the card: Knowledge and Leverage. It's amazing how often people just leave their cell phones laying around with so much sensitive data stored on something that can be so easily removed/swapped out... The great thing about it is, if you replace the card with another one, most people just think their phone fucked up on them and if you're good enough you can dump an SD card in a matter of minutes and return the card before they ever suspect a thing.
I don't steal for fun or impulse, my nefarious acts are usually premeditated and run against a risk vs value assessment. Which is why I've never been caught.