I believe I read that Wasabi has EM5 batteries. I use a couple in my G3 alongside Panasonic batteries and they do fine--at $7 or so a battery too. Not chipped.My suggestion is to call around to some shops in random places and just ask if they've got them in stock. Also, if you are shooting it for paid events perhaps lob a call into Olympus.
Wasabi Power OMD replacement batteries - Good stuff: Micro Four Thirds Talk Forum: Digital Photography Review