In general, ending inventory is valued at cost. That would be the cost of the wood, finishes applied to the wood, etc. Whatever it cost you to make the finished product that is in your ending inventory. Market would refer to if you used the method of inventory cost or market, whichever is lower. That generally applies if you bought the inventory, and then you were going to reduce the selling price to below cost, or if the "market" for those goods declined, what would the market price be to replace the inventory.
See Publication 334 for more information and other tips for filing Sch C.
https://www.irs.gov/pub/irs-pdf/p334.pdf
Instructions for Sch C
https://www.irs.gov/pub/irs-pdf/i1040sc.pdf
Also review Publication 538, Accounting Periods and Methods; See Accounting methods on page 8, and also Inventories on page 13 for further guidance.
**Disclaimer: Effort has been made to offer correct information; but due to the discussion forum limitations, the poster disclaims any legal responsibility for the accuracy of the poster's response**
