easy. with 100 barter you could sell item with 100 cod. to store for alot of moneykill fiends, gang members, powder gangers, or other random enemy types and sell their armor and weapons.
I suggest fiends when you get to a high level because many will carry energy weapons, usually plasma/laser rifles or the new Laser RCW. Just loot the weapons and repair them useing other weapons you may find, also they may leave behind alot of ammo for these weapons if you have the scrounger perk.
making caps is not hard at all ive never taken scrounger or worked on barter til near end game. just scavenge thats what everyone else does. pick up items that have a good weight to cap ratio lighter items that are worth more as oppposed to heavy items worth less and sell eveything you dont need or want.