What is a non-cost methods to value inventory?

Well under some situations inventory valuation is impractical. If  the market price of a commodity fall below its cost price the lower of cost or market method of valuation is recommended.

This method allows declines in inventory value to be offset against income of the period. When goods are damaged or obsolete, and can only be sold for below purchase prices, they should be recorded at net realizable value. The net realizable value is the estimated selling price less any expense incurred to dispose of the good.