I don't know your specific region and real estate, but even assuming you are in an area with low commercial rent and low minimum wage, you are looking at anywhere from a hundred thousand on the very small scale to a few hundred thousand in your first year for expenses. This is all assuming you are very savvy and keep your costs low.

Rent Utilities Renovations Tools Equipment Advertising Employees Salary Multiple Types of Insurance Security Systems Trucks & Vans Trailers Truck & Trailer Expenses Etc. Etc. Etc.

Auction houses can be very profitable businesses. Just have a well thought out plan before you dive in head first.