I never find any duct tape at MERCHANTS even though the wiki says they should be selling it

[[A]ndrew]

http://fallout.wikia.com/wiki/Duct_tape#Locations

Restocked once every three days by Ralph at Mick & Ralph's, the Gun Runners kiosk and at the Gibson scrap yard.

Occasionally sold at the Goodsprings General Store.

I never once found it for sell at any of the vendors mentioned above. I'm level 29 btw.

I need the duct tape to craft weapon repair kits.

[Ladez]

Maybe this'll help:

http://www.nexusmods.com/newvegas/mods/44671

[[A]ndrew]

B-b-but... muh immersion!

Also 100 rolls at the same vendor makes it too easy.

[talgaby]

Just use the book chute from OWB. Although WRKs are penny a dozen with Dead Money.

[[A]ndrew]

I haven't started playing any of the DLC's yet

[Improper Use]

The largest aingle vendor stock is 6-10
open console and add 20 manually, save game, close game, restart and reload.
Store 10 for next week.

You can carry on now.