RPGaDay #30 Rarest RPG Owned

Rarest RPG owned?   I mistook this for oldest RPG owned (not necessarily still read) and was ready to post pictures for the Revised City-State of the Invincible Overlord.   The problem is that the 80 page book went through three different printings.  That might be a substantial enough print run to push it past the "rare" category despite it's age. 

And rare does not automatically connote valuable.  The sheer demand for older D&D books drives the price of them into the range of hundreds of dollars.  Sure the white box has become rarer and rarer over the years, but I've seen three of those bad boys in the last decade.  I'm the only person I know who has (much less seen) a copy of The End and I'm assuming that print run (in the d20 glut) was much higher. 

So what item do I still own that has a low print run and pretty impossible to obtain.

Here's a curveball... The T.W.E.R.P.S. Files by Reindeer Games.

Despite their low-cost between $2-4 apiece, TWERPS and its bevy of supplements enjoyed  decent (if not profitable) print runs and sales thanks to the ads that ran in old issues of Dragon.    The T.W.E.R.P.S. Files suffered from being the twelfth and final supplement produced for the game.  I can't remember ever seeing another copy of it beyond mine (and trust me it's one of the lesser products in terms of information and the trademark punny names.)

In searching for a picture, I did discover a nice blog with TWERPS love, that also includes the unofficial thirteenth supplement Adventures in Time and Spacey-Wacey.