a sole proprietorship operating a business that is not real estate rental files schedule C. a single member LLC is a disregarded entity from the IRS viewpoint. conducting the same business means it to would file Schedule C.
from a QB viewpoint just ignore the fact it's an LLC and continue the bookkeeping as if it's a sole proprietorship. then there are no transfers of inventory that need to be recorded.
for tax purposes inventory can not be depreciated. however, it can elect various methods for valuation such as cost, lower of cost or market or another method that clearly reflects income.
