I love to digg in the ebay world and I made a list of the stuff I found for all current (and future) E-M5 owners. it may help you out to find something you need.
There is the official CS-36FBC Olympus case. A leather half case from Hong Kong. A full leather case with strap from Cina. Than we have half cases from two well known producers, Zelenpol, Kaza and Gariz.
Batteries, and other things:
The Olympus GS-4 strap and the DSTE E-M5 batteries you have to use with an extra charger. There is an E-M5 car charger a new E-M5 LCD screen and a Front Cover+ Top Panel.
Let me know if you find more stuff! Thanks!
Some E-M5 preorder links: Amazon, Adorama, B&H, Jessops, Amazon UK, Amazon Germany, Amazon France, Amazon Japan and Digitalrev.