Audrey Hepburn & Marilyn Monroe Caps?!!
You have excellent taste sir, I commend you.
IMSTO is taking some time off from selling keycaps, IIRC. Try feng, who is his friend/ business-partner/ cohort (actually I don't know what their business relationship is - maybe even competitors). Anyway, if you want Chinese made custom PBT caps, besides IMSTO, your best place to look is feng.
Here is best contact info I have:
http://www.ebay.com/usr/geek_fengMaybe some other GH'er has better info. GL
I hope you find those Audrey and Marilyn Caps.