What are my options for flash for the GH1/GF1?

Is there a cheaper 3rd party flash for the Panasonic GH1/GF1 cameras with TTL functions? I’ll want it to have full tilt and turn functions too.

If there are no 3rd party TTL flash for the pana cameras then I’ll have to resort to 3rd party flashes with automatic sensors….. and I’ll have to manually adjust my aperture with the settings on the flash?????