I always assumed economics was the study of decision-making where--pardon my fiat!--dollar values could be assigned.

I would differentiate finance as the application of that study at a more local level, and accounting as a similar optimization of that application in the face of regulatory restrictions.

Small businesses have all sorts of policies and protocols built on assumptions of what would be profitable, in line with their values, and according to their strategic plans. So if we are saying economics must deal with policies to be economics (which I am not ready to concede to), it seems economics does apply to small markets/businesses.

Economics is the study of human action under conditions of scarcity. It is every bit as much about entrepreneurship as about government policy.