I'm not a wannabee corporate-raider, and my clients don't want/need me to be, so suits at a consult are out of the question for me!
Am I a business man? Yes. But at the same time, my clients understand that there WILL be a difference between what is worn at a consult and what will be worn at their formal event, and I always bring up attire at the consult and include verbiage for it in the contract they get, so it is understood that while I'm not in my "Sunday Best" for the consult, I will be attired as desired/required for their event - which is all they care about.
I'm not saying be slovenly or unkempt... keep it nice and clean and presentable, but be up-front about who you are, and be up front about how you will present yourself when it counts - at their event.
That you're "a professional" and a "businessman" isn't conveyed to them by your attire at consults as much as it is by your demeanor, your confidence, your attention-to-detail, your knowledge and conveyed experience at what you do, etc.
Unless you're swinging to the complete opposite end of the spectrum, they don't care what you look like at Starbucks, as long as you present yourself right from the time of that first phone call or email. Seal the deal by bringing up their desired/required attire at the meeting, discussing it, and including it in your written contract, and they will be fine!
Attire is perhaps the most insignificant aspect of a consult that we should be concerning ourselves with.