Just Looking, Virginia
The valuation methods for commercial and residential properties differ. In the latter case, one uses a CMA to determine that value. In the prior case, one uses the income to determine that value. You need to get the rental comps and vacancy rate for the area, and some other market data to get a better idea of what to charge for rent. Also, keep in mind that commercial rents are usually given in terms of price/sf/year and the amount of rentable space.