I prefer the term "geek" personally. Indeed, I have a navy blue t-shirt with that single word on it that I often wear with my Scottish National kilt. Looks great.

Anyway, I believe I've seen a pic of a sporran with one of the Transformers symbols on it posted here. But I'm sure it was handmade or custom-made. So if you are able to pay for the personalization, I'm sure you can find someone to attach or emboss or whatever some appropriate symbol onto some leather for you.

Good luck!