As someone who, in the good old days, was the proud ownder of a d100, I believe a number of comments are in order.

A d100 is huge - not something you want to carry in a pocket.

Once in motion, it keeps on rolling. (see below)

Numbers are tiny, which makes it very difficult to use.

They are easy to lose. I owned a d100 for a couple of weeks. During a RPG convention, I used it for demonstration purposes only.
It went... the table...
...down a flight of stairs...
...after being reflected off a wall, down another flight of stairs...
...and lost from sight.
It then either disappeared into nothingness or (more likely) found a new owner among the hundreds of RPGers.

JayBonci is right - not that that would surprise anybody.
Unless you have spare cash, a set of d10s is a much better buy.