For shoe laces get something called Iron lace http://www.ironlace.ca/Products i have had one set through three sets of hiking boots, a friend has gone through 2 sets of work boots as a surveyor same laces.
Any type of water purification tabs
Batteries everything runs on them, even the ability to recharge them.
Blacksmithing for tools and repairs
alcohol is simple to make http://www.instructables.com/id/How-to-make-a-still/ get a few candy thermometers to know when it changes from methanol to ethanol. methanol is useful so long as you dont drink it. Ethyl alcohol produces Iodoform(CHI3),a yellow crystalline solid with Iodine and NaOH.Methyl alcohol does not respond this test.
Canning jars with tattler lids, this is a trade with friends so you can get back lids and jars so you can reuse. Tattler are teflon reusable lids.
Lighters and refill ability, made a butane recharger for lighters that fits on to a big butane tank.
freeze dried antibiotics and baclostatic water and hypodermics.
Ability to work leather and tan hides with brain tanning skill. if o skill you can still sell strips/pieces
Doctor skills, along with salves and tinctures
Plastic rolls and bags of 6 mill or higher
Toilet paper, wet wipes, diapers reusable rash creme , i would never sell the condoms too many uses for those things.