I am having a hell of a time getting the chainline perfect on my fixie.

I have an IRO hub with Soma 3/32" cog. Sheldon Brown's site says this should give a 42.37 mm chainline, but I am measuring it to be about 43.5. Up front I have a Sugino double crank with the chainring sitting on the inner part. I'm measuring it to be about 43-44 mm. I can also tell that the chainline is close to perfect because when I look at how the sprocket teeth sit between the chain plates, they're about .5 mm off center.

And yet I'm still getting a real loud clicking noise from the cogs, about as bad as if I were to flip the chainring over and have the chainline off by 2 mm. Could there be anything other than chainline causing this? Nothing I've done seems to improve it... I've heard there are bottom brackets that allow fine adjustment of both cups. Are these expensive, and if not too much, where can I buy one?