In reply to Simon CD:
Definitely not to be recorded as the sale price of the bags since you haven't even put the labour in to make the bags (not to mind the risk you cannot sell the bags, etc.,). Otherwise you could increase the book-value of your business by taking cash and simply buying fabric and putting it in store.
When you have work in progress, things get more complicated and you may want to think of valuing work in progress as some intermediate value of raw materials and final value.
SimonCD's answer seems good. Don't know if sometimes you would use the replacement value of the fabric (but only if it still has an economic use to your business). Certainly when you're doing cost accounting you get into that sort of calculation.