Is there a reason I would go to BMW for an alignment that costs $175 as opposed to my local guy whom I have used for years that will charge me $45? Special tools, methods, etc?

nope, make sure your local guy has good equipment. otherwise he will get the same specs to align you car as the BMW dealer does.

Has your local guy done an alignment on your BMW before? This topic has been discussed before on here and the going rate for an alignment ranges from $150 to $300. Some local guys do not have the equipment to give a proper alignment to a BMW, which requires all four wheels to be aligned, not just the front wheels.

And depending if you have active steering, which isnt listed in your sig, so I assume you dont, but if you did they really need to have special equipment and skill to align it.