Shaun,
Business visa's are very much like a tourist visa, except that there purpose is for business, so they are very much temporary, and limited in duration. Great to get your lady over for a visit, but not much else, and certainly not to run a small business in America. I'm pretty sure she would need a green card or similar to do that.....
I'd stick to the Spouse visa, but there's nothing to stop you bringing her over on visits if she can prove that she has a business, and preferably an export business.
Business visa's are normally granted by the commercial sections of embassy's/consulates rather than the immigration section...
David...