when in a crafting market such as making netherweave bags, don't craft up all of you items to the final end product. Make sure to leave some at various steps along the way, so that if the market changes on you, you have other options and are not stuck. You don't want to be forced to sell low or have a long period of waiting out your competition.
Case in point: On my server people have started to catch on to the Bag Market so bags have been cut down to 8g per. Ok so I can still sell them at 8g for a profit since I buy stacks at 6g or less, but as the market for bags has dropped the price the cloth market has skyrocketed. I am selling those unbolted stacks for 15g each, well beyong what a bag even sells for, and I am also selling bolts of netherweave in stacks of 4 for 12g each. So i am playing all 3 markets at the moment, turning 6g into 8, 12, and 15g all three. If I had burnt all my mats and stored just a bunch of bags, I would be stuck selling for lower than I know I can get for these bags, As i always sell out at 10-12g and rape at up to 25g per sometimes, when the time is ripe.